Ergonomical Opinionings Requesterated


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barnbwt
April 29, 2014, 10:44 PM
So I'm working on a design for a rifle intended for the purpose of introducing new shooters to semi-auto center-fire. I have a number of features devised to make things easier and more intuitive for them, which I'll list below in case you'd like to suggest/add things. (Please refrain from turning it into an AR ;) ) I've figured out how I'd like to do nearly all of these, with the exception of a grip safety that also automatically switches the ejection direction for left or right handed shooters.

My current design, The Skorparev, has either two ejectors or two extractor claws (haven't decided which should be switchable to best direct the ejection path) of which one will be deactivated depending upon which side the ambi- grip safety is depressed. The only trouble is it's hard to decide the best place to put such a device so that it is reliably engaged, on one side only, and isn't obnoxious. Presently, my thinking is to put a lever/button under very low return spring tension either;
-Just behind the trigger lever on each side, where the base of the shooter's finger would depress it to wrap around the trigger
-Or even further back where the shooter's index knuckle would press against the stock when they grip it
-As a thumb rest on either side of receiver tail

They each have pros and cons, of course, which is why I seek ya'lls' opinions. The first solution makes the trigger feel weirder, sort of like a Glock lever but on a rifle. The second is much more exposed to inadvertent activation if the manual safety is left disengaged, and may be sensitive to different hand shapes. The third is thumb activated, so more likely to be missed by shooters with a different grip or hand shape, but can probably require more force for activation without being annoying. The compact, light rifle would also be great for carry, so making it sling-safe (with manual safety) is a priority, and scabbard-safe with the manual safety off (but grip safety deactivated until needed) preferable.

I've got material on hand for the receiver and will be cutting metal very soon, so I need to get this last detail sorted out! :)

http://www.thehighroad.org/attachment.php?attachmentid=197275&d=1397367201
-All controls and functions completely/automatically ambidextrous
-Good quality two stage trigger
-M1 carbine adjustable iron sights
-Manual and grip safety (manual safety locks grip safety)
-Manual safety protrudes into thumb palm of strong hand when engaged
-Grip safety deactivated by strong hand
-Left/right ejection switchable based on shooter's grip (left or right)
-Non-reciprocating charging handle built into foregrip
-Large mag release thumb-paddles on both sides, set flush with sides
-Last round bolt hold open, manual cock bolt hold open (see next)
-Forearm automatically releases a locked-back bolt when re-gripped
-Fast, low recoiling cartridge for unintimidating, flat shooting practice (7.62x25 for now)
-Small, lightweight construction/profile suitable for young/grown shooters of all sizes
-Uses PPSH mags/drums of all capacities
-Straight, wooden stock to alleviate any 'military' aversion by anti's/new shooters* (until I pop the drum on after a few 10rnd stick mags ;) )
-Convertible to a pistol format** (by virtue of the receiver being constructed a 'firearm' per current ATF regs ;) )
-Externally-visible Degtyarov-inspired gas operated locking system

TCB

*This is to try to disabuse new, ignorant shooters of 'Assault Weapon' sensitivities
**This is to try to inform new shooters of the asinine nature of NFA/ATF classifications rules

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Tophernj
April 30, 2014, 08:14 AM
Personally I like the idea of the safety being just behind the mag.

Cool concept. What will it be chambered in?

C

barnbwt
April 30, 2014, 08:43 AM
It's slated for 7.62x25 at the moment, though I think it will end up (for now) in a 223 brass-based version of Tokarev (not much left, and too spendy). Probably close enough the x25 can still be fired safely, but with a fatter neck so the 223 brass' thick walls won't need finish reaming after necking down.

The buttons right behind the mag are currently the mag releases; do you think it'd be a better spot for the (manual) safety? Where would you reposition the mag release?

TCB

barnbwt
April 30, 2014, 09:01 PM
I could really use the opinions, ya'll. Think of it as your chance to make history, for no pay! :p

TCB

barnbwt
May 1, 2014, 11:40 PM
No takers, eh? Kinda tight-lipped around here, for once... ;)

TCB

Nom de Forum
May 1, 2014, 11:52 PM
No takers, eh? Kinda tight-lipped around here, for once... ;)

TCB


Give me some more time to reply. I looked at it within minutes of your posting it and think it deserves serious consideration before comment. Unfortunately I have been delayed due to being busy investigating historical comments in posts and PMs with reasonable minds, and receiving unrelated insulting PMs from an unreasonable mind. What I can say is the intention of your design is very admirable.

WestKentucky
May 1, 2014, 11:58 PM
I would like to see it bottom eject.that way it doesn't bother either lefty or righty. No need for fancy buttons and such, besides if your trying to have reversible extractors, what happens if both go active? Would be a nasty stovepipe to clear. An oversized mag well should let you bottom eject to the side of the mag with no issues, if you wanted you could make a double-wide mag with one side hollow and bottomless to eliminate loading issues where there's an extra hole.

Nom de Forum
May 2, 2014, 10:11 AM
Did you by any chance post this thread just to give all of us a headache?

I've figured out how I'd like to do nearly all of these, with the exception of a grip safety that also automatically switches the ejection direction for left or right handed shooters.

That is going to be really hard to do and gives me a headache just thinking about it. Is this feature really necessary?

Manual and grip safety (manual safety locks grip safety)

How will the safeties actually prevent discharge? Will they lock, block, or redirect the firing pin? That would be a good feature.

3lb Metallic Weight (empty)

What do you anticipate the weight will be with a stock and forearm attached? You state you want to keep the weight down, so why wood and not a synthetic stock and forearm? Synthetic does not have to appear military. Are you also going with wood because it is easier for you to personally create?

Non-reciprocating charging handle built into foregrip

Consider making a folding charging handle ala HK91 to clean-up the appearance and eliminate snagging on hands and arms.

Ok, that's all for now. I've got to go take some aspirin.

primalmu
May 2, 2014, 06:24 PM
I might be off base here, but I feel like an SKS would fit the bill just as well, and would be cheaper to buy and cheaper to feed.

barnbwt
May 2, 2014, 07:30 PM
"I might be off base here, but I feel like an SKS would fit the bill just as well, and would be cheaper to buy and cheaper to feed."
Won't even dignify that with a response...just kidding ;). This is the first from-scratch design I'm going to bring to fruition; off-the-shelf isn't even an option for me, that's not the real purpose of this exercise. My first design was a tilting-bolt action that was actually markedly similar to the SKS, but I quickly found the design doesn't play will with drums, which was a deal-breaker. The SKS is also a vastly larger and heavier rifle than what I'm going for, being a full-size battle-rifle type gun. This one's a definite plinker, more like an M1 carbine but with better magazine capabilities.

"Did you by any chance post this thread just to give all of us a headache?"
Eh, I stopped noticing the migraines a few months back :D

At the risk of losing my 'million dollar idea,' (;)) I've attached a few more operational/detail pics of relevant parts to clarify what's happening.

"if your trying to have reversible extractors, what happens if both go active?"
The extractors are at 10:00 and 2:00 (or ejectors at 7:00 and 5:00) so I ASSume a dual-activation would throw the brass straight up or damage one/both extractor (I'd obviously try to design the hook contours to avoid the latter). The design was originally a straight-up ejection, with lines based roughly on the PPSH-41 (also in 7.62x25, but a direct blowback action that left the rifle heavy, harshly recoiling<compared to a locked breech>, and with a terrible trigger), but scaled to something more the size of a "tactical pistol" (Skorpion, MAC10, mini Uzi, etc.). My design progressed to an 'open' action that allowed for a very large ejection port up top, so I figured why not try to get the rounds to deflect to either side and make the gun even more ambi-friendly? Since vertical ejection is a compromise that favors neither, and may irritate/disturb new shooters trained on the front sight :)

"Is this feature really necessary?"
No, but I think it's easier than I expected at this point. You either:
1) Have two pivoting extractors, and have a bump on their tails that engages a selectable lever when the bolt retracts, which would cause the selected extractor to pivot up off the rim of the case just as the fixed ejector punches the far side of the case head
2) Have a single extractor claw in the middle, and to parallel plunger ejector pins in the bolt. Only instead of being driven by a stiff spring, they contact a rigid surface (the back of the receiver tube) at the end of the bolt's travel, at which point they act like a fixed-blade ejector to aggressively punch out the spent case

It's complicated to describe, but would be extremely easy to understand/operate in practice (assuming it works well), and really only adds two extra parts (the extra ejector or extractor, and a selecting lever)

"How will the safeties actually prevent discharge? Will they lock, block, or redirect the firing pin? That would be a good feature."
There is a sliding safety that protrudes into the thumb web when active. When slid forward (it's more positive than a grip safety) it will cam the hammer back off the trigger/sear, and lock the trigger/sear into place, and slip over the same sear surface as the disconnector to alternately block the hammer if the primary part failed, somehow. The grip safety will simply interfere with the trigger's movement until it is depressed. The trigger itself is a little different than what we're used to; it's a two stage where the first stage it pivots under little load, and then slides straight backward off the sear contacting nothing but the sear, the pivot pin, and the shooter's finger. The hammer and trigger are similar to a Giesselle AR15 format (i.e. AK47 ;) ). Disconnector is a hammer-actuated sliding type that does not bear on the trigger except during reset. Should be a very nice trigger if I can make it good quality :cool:

http://www.thehighroad.org/attachment.php?attachmentid=197364&d=1397617210
As far as firing pin safeties, the locking piece actually retracts the firing pin mechanically when it moves backward (just like the Degtyarov) making a very effective OOB safety. There is no pin safety when fully in battery, which is why I am considering making the bolt hold-open lever on the foregrip actually pull the bolt/carrier backwards a fraction to block the firing pin, when not depressed by the shooter's weak hand. Other than the need for ejection selection, the grip safety role could be filled by such a device. I am undecided though, since such a design that requires two hands to operate is a limitation I'm not certain is a benefit (to new shooters, yes; to me, perhaps not; to me drawing the rifle from a scabbard, absolutely)

"What do you anticipate the weight will be with a stock and forearm attached?"
About 1lb of that is just the barrel, btw, which I think is a really efficient ratio :). The real question, is what do I anticipate the weight will be with a full 71rnd drum attached :D. The stick mags ain't lightweight, either (I'd have a ten-rounder made up for walking around, most likely). The stock I'm using is another few pounds, so my hope is for ~6lbs or so with a mag but no ammo at the end of the day.

"Are you also going with wood because it is easier for you to personally create?"
Yes. Exactly that. The stock could be a pretty low-density affair with a hard finish, since this gun isn't exactly meant for hard recoil or butt-stroking. Cyanoacrylate-sealed Basswood would probably work, but for now, I'm using the chopped up pieces of a Steyr M95 stock (it's not suited for the recoil of 50 Alaskan that the action is being rechambered to ;) ) to form the butt and foregrip. See attached (early) mockup pic.

"Consider making a folding charging handle ala HK91 to clean-up the appearance and eliminate snagging on hands and arms."
I liked the idea and was planning on it some time back, but then I found out about how much everyone hated the Reissing's flush folding handle in the foregrip, which is exactly how I'd planned to do mine. Kinda soured me on the whole concept of a 'hidden' handle, but if you can think of a better solution please speak up. Maybe make the 'swell' (or whatever the German word for it was) at the tip of the foregrip into a knob or ring that is grasped to cock the gun?

What's more odd about the foregrip design, is that when the charging handle is pulled back to cock the gun, it will automatically hold the bolt open. When the handle is allowed to return fully forward by a return spring and then grasped by the weak hand, the bolt catch will disengage and drop the bolt into battery. Again, sounds complicated, but makes total sense; the bolt locks back when you manually pull it back to check or on an empty mag, and only releases when you grip the gun to shoot it. Not ideal for chambering a round quietly, but that's what the system of safeties is for: cocked and locked carry in a rifle :cool:

"Did you by any chance post this thread just to give all of us a headache?"
Maybe. I undertook this project with the intention of making a gas-op locked-breech pistol caliber carbine, since there are very few out there (MP7, MPX, and that's about it if you aren't counting cut-down ARs/AKs). But, drunk on the total freedom a scratch design carries, I thought I should re-examine the very foundations of weapon ergonomics that, I felt, were rooted more in long-extinct designs (bolt action handles, selector levers) than in what is intuitive. Gunnie version of navel-gazing, I suppose ;)

TCB

Attachment Key:
1) FCG Concept (proof of concept soon to follow, hopefully)
2) Very early mockup of the parts I had at the time
3) Older-configuration view of the large ejection port and exposed action with a VZ52/Garand FCG (possibly bad for debris, but great for demonstration)

barnbwt
May 4, 2014, 11:34 AM
I've at least convinced myself that, no matter how the bolt/safety design shakes out, it will not have much impact on the receiver tube, proper. Therefore, I've decided to proceed with cutting metal for the locking recesses, mag/ejection ports, and FCG opening. I can pretty complete the rest of the project without any extractor or ejector, and solve those problems once the rest of the platform is set in stone (or steel, to be specific).

"An oversized mag well should let you bottom eject to the side of the mag with no issues, if you wanted you could make a double-wide mag with one side hollow and bottomless to eliminate loading issues where there's an extra hole."

Don't know how I missed your comment earlier, but thanks! In this case, I can't eject down by the magwell since I'll have drums in the way, and the PPSH stick mags actually have little 'ears' on their sides to emulate the top surface of a drum. But... one of my side projects is a belt-fed VZ58 conversion, and the idea of ejecting through a hollow magazine may be the solution to my ejection dilemma. I cant' eject up since the belt and top cover are in the way, but I don't need the magwell for anything but to hold the RPD drum box in place. So there's no reason I can't remove one of the side walls of the 'feed tower' sticking off the top of the box to latch it into the magwell, and figure out how to get rounds to go down instead of up (probably just removing the extractor would be the easiest solution for a simple conversion, probably modifying the bolt head for a bottom-claw extractor in the slot the blade ejector used to go, and a button-type ejector on the opposite side or where the extractor claw used to go). But that's for another thread :)

TCB

Nom de Forum
May 4, 2014, 12:05 PM
barnbwt - "Consider making a folding charging handle ala HK91 to clean-up the appearance and eliminate snagging on hands and arms."
I liked the idea and was planning on it some time back, but then I found out about how much everyone hated the Reissing's flush folding handle in the foregrip, which is exactly how I'd planned to do mine. Kinda soured me on the whole concept of a 'hidden' handle, but if you can think of a better solution please speak up. Maybe make the 'swell' (or whatever the German word for it was) at the tip of the foregrip into a knob or ring that is grasped to cock the gun?

I agree a flush mount would be disliked. What I notice from your diagrams is how short the forearm is and how big the cocking handle is sticking out from the bottom. It is not very aesthetically pleasing IMO. There is very little room for the hand next to the cocking handle. When you attempt to zero the cocking handle is going to rest on the sand bag and not in a good way. How about extending the length of the forearm, place the a folding cocking handle at the end of the forearm but not flush inside it. The shooter would then extend his arm more but his hand when shooting would have more room. There would be no interference from the cocking handle when resting the rifle on a sandbag for zeroing. What I envision is a cocking action similar to a under-lever air rifle but without the long lever or flush mount. The cocking lever would have a the casual appearance of a gas tube under the barrel at the end of the forearm. Now that I have discovered justin22885's thread about designing a new rifle, which you have contributed much, I am grateful to only have a headache from thinking about your thread and not a stroke from justin's thread.

barnbwt
May 4, 2014, 12:42 PM
There's no way I'm extending anything on this rifle :D. I'm trying to keep it as light and compact as possible, since that was an original design goal (to make a locked-breech carbine capable of shooting high-end pistol-class rounds like 10MM or 9x23 and significantly more compact than an AR pistol-caliber conversion) and because it also works well with the introductory carbine/bantam carbine/trail carbine roles. Heck, I fully expect to SBR the thing back to the receiver tube eventually, for something about the size of an MP5k with a much more compact receiver/lower and much higher cartridge power capability.

"It is not very aesthetically pleasing IMO"
Indeed. Indeed :(. The index finger actually sits in front of the handle during shooting so it's a lot roomier than it looks. Thinking along the lines of a BB gun pump handle (mine were lever action as a kid :D) I think it'd be possible for the handle to fold forward into the schnabel forearm* and be mostly hidden but for the tip which would stick out the front and be readily snagged by the index finger for cocking. The new shooter would be less likely to try to pull back on it while shooting, too (my primary concern with its current location all along). While it's locked in place by the bolt catch lever, if that is released during firing, tension on the cocking handle would pull it back some and the returning bolt carrier would smack the hell out of the shooter's finger :(.

TCB

*Man, that word's been killing me for like two days :D

Ro1911
May 4, 2014, 01:16 PM
Why not just make this a 9mm and use Suomi mags? Or make it 7.62x25? I don't get the appeal of making it a wildcat 223 thing that only you and your handloading buddy's are going to like, 7.62x25 is available at about the same price as 45 and 9mm is cheap usually.

Plus 9mm doesn't have a neck which is good for reloading if your so inclined

Nom de Forum
May 4, 2014, 01:25 PM
[QUOTE]There's no way I'm extending anything on this rifle :D. I'm trying to keep it as light and compact as possible, since that was an original design goal (to make a locked-breech carbine capable of shooting high-end pistol-class rounds like 10MM or 9x23 and significantly more compact than an AR pistol-caliber conversion) and because it also works well with the introductory carbine/bantam carbine/trail carbine roles. Heck, I fully expect to SBR the thing back to the receiver tube eventually, for something about the size of an MP5k with a much more compact receiver/lower and much higher cartridge power capability.

I did not mean to imply turning it into a Garrand. I was thinking two or three more inches and ounces for sure if you are going to keep the gaff hook cocking handle and more room to make the folding handle attractive.:)


"It is not very aesthetically pleasing IMO"
Indeed. Indeed :(.

Sorry, you asked for opinions and think you want sincere ones. I am sure when it is all done your nearest Museum of Modern Art will request a copy for their display of outstanding modern design. It will be right next to the Movado watch.:D


I think it'd be possible for the handle to fold forward into the schnabel forearm* and be mostly hidden but for the tip which would stick out the front and be readily snagged by the index finger for cocking. The new shooter would be less likely to try to pull back on it while shooting, too (my primary concern with its current location all along). While it's locked in place by the bolt catch lever, if that is released during firing, tension on the cocking handle would pull it back some and the returning bolt carrier would smack the hell out of the shooter's finger :(.

The text of your quote I placed in bold type is similar to what I was attempting to convey. I think you are on the right track with this idea and should abandon the gaff hook.

Please remember that no matter how much I crudely sugarcoat my suggestions for your baby boy it is natural for a proud father to feel a little sting. :D

barnbwt
May 4, 2014, 02:18 PM
"Why not just make this a 9mm and use Suomi mags? Or make it 7.62x25? I don't get the appeal of making it a wildcat 223 thing that only you and your handloading buddy's are going to like, 7.62x25 is available at about the same price as 45 and 9mm is cheap usually."

PPSH mags are awesome since they are straight-line single feed, which is probably the most reliable type there is, and the extra length they have over the original Suomi design allows for a ton of cartridge options. At 9mm length, you're basically relegated to 9mm, and have a very hard ceiling on the power levels you can develop. The PPSH length can accommodate 10mm length offerings, if I remember correctly (with shorter bullets it for sure can) and the sticks can feed 45acp with lip alterations (40cal is about as much width as the drums can accommodate without massive modifications)

9mm will feed from PPSH mags (not drums, though :() and a spacer/adapter for the mag well could probably allow it to take the shorter Suomi mags (sticks, drums, and coffins :) ). It is in 7.62x25, but the surplus ammo is now so expensive and often unavailable, and reloadable factory ammo even more so, that folks are looking back at converting 223 brass into tok brass. The problem is the case body is thicker when trimmed back that far, so tedious neck reaming is required. I thought, "why not just make the neck of a tok chamber a few thousandths thicker so you don't have to do that?" Now you have a ready supply of convertible, cheap brass, that's also capable of 223 pressures (60ksi vs 35ksi for 7.62x25) which might make for very interesting ballistics from such a small cartridge/rifle. Moreover, aside from the extra neck room possibly allowing already-split-prone necks to split and 'ruin' unreloadable brass, there's a very good chance standard 7.62x25 would work just fine.

"I was thinking two or three more inches"
The receiver tube is 10" long; that's a 20-30% increase in the core part of the gun I can't chop off for an SBR. Also, the fact there's a drum there means your hand has to be at a 90deg angle to get around it, so a diagonal grip that takes more room on a foregrip isn't as necessary as a longer rifle.

"Sorry, you asked for opinions and think you want sincere ones."
You misunderstand; I never particularly liked the look of the cocking handle down there (check out a FAMAS or early AR10; it never looks good). It was always the biggest aesthetic compromise on the gun by far (well, the square tube receiver is a close second ;) ) but I just couldn't see a good safe place for a reciprocating handle anywhere, or a place to put a non-recip handle that wasn't jutting out the sides or into the line of sight. That left the bottom, and specifically the foregrip.

Ooh, here's an interesting idea, borrowed from Czech heavy machine guns; slide the foregrip forward to snag the bolt carrier, and pull everything back until it releases at the very end. Maybe an ambi-detent button on either side you have to press to unlock the grip and slide it forward.

"I think you are on the right track with this idea and should abandon the gaff hook."
Abandon the hook for a forward-pointing "sinister beard"; got it :D. Only possible problem I'd have to watch for is that reaching past the foregrip tip is really close to a barrel that may have just had at least 71 rounds dumped through it. Would have to keep ergonomics in mind (they are touchy enough already since the gas release port is at the first set of lightening cuts above the thumb/index fingers, but at least the cuts are smaller than finger tips :eek:)

TCB

barnbwt
May 4, 2014, 02:19 PM
Great feedback, guys, keep it coming. I'm glad the overall concept of the rifle sounds like something worth pursuing :cool:. Just gotta get the little details where most folks would probably like them and I think I'll have a winner.

TCB

henschman
May 5, 2014, 02:41 PM
Cool idea overall, but I would never own a rifle with a grip safety, and would certainly never use it to teach new shooters. For classic field position type shooting, like we teach at Appleseed, we teach that the only part of the trigger hand that is putting pressure on the grip is the bottom 3 fingers, pulling the grip straight to the rear to keep the stock in the shoulder pocket. Furthermore, we frequently have shooters rotate their hand around the stock so their thumb isn't wrapped around the "wrist" of the stock, to keep their trigger finger from "dragging wood." I wouldn't want to encourage the type of gripping that would be necessary to actuate a grip safety on a rifle.

Nom de Forum
May 5, 2014, 07:58 PM
Cool idea overall, but I would never own a rifle with a grip safety, and would certainly never use it to teach new shooters. For classic field position type shooting, like we teach at Appleseed, we teach that the only part of the trigger hand that is putting pressure on the grip is the bottom 3 fingers, pulling the grip straight to the rear to keep the stock in the shoulder pocket. Furthermore, we frequently have shooters rotate their hand around the stock so their thumb isn't wrapped around the "wrist" of the stock, to keep their trigger finger from "dragging wood." I wouldn't want to encourage the type of gripping that would be necessary to actuate a grip safety on a rifle.

It will be interesting to read barnbwt's reply to your post. Until then, I don't think this rifle is intended "for classic field position type shooting". It is my impression it is being designed for the pleasure of creating an unorthodox design and for users who are very inexperienced, like the safety features, are interested in plinking and self defense with something more exciting and powerful than a .22, will most likely never be interested in "classic field position type shooting, and want something relatively inexpensive. I also have to wonder if barnbwt's grip safety design will cause the same number of problems with accuracy as the grip safety on a Colt Gold Cup. That number being 0. If done right, barnbwt's grip safety may have the same number. This is just my impression and I really hope barnbwt will soon provide clarification.

briansmithwins
May 5, 2014, 08:24 PM
For absolute ambidexterity in ejection consider using a system like the FS2000. There is a ejection tube that parallels the barrel. Empty cartridges are placed in the ejection tube and drop out near the front of the forearm, out of the way.

For ambidexterious charging, I'd consider a pump forearm as it's easily worked by either hand.

Grip safeties and firing pin blocks are generally overkill for long arms. Each thing you add increases complexity and cost while reducing reliablity.

BSW

sawdeanz
May 5, 2014, 08:31 PM
The most interesting part of this is the automatic ejection feature if it was simple enough and worked well, because it could be an interesting or even very effective solution for ambidextrous use during tactical work, which most ambi rifles lack (for example an aug or tavor though ejection can be switched, isn't automatic which would benefit off hand shooting).

However I think for your stated purposes, it just adds more buttons and features than a new shooter would know what to do with, and the same goal could be achieved by an adequate shell deflector.

I know the idea is to kill two birds with one stone, but I think it would be kind of hard to reconcile the two purposes, but maybe I'm not understanding the intended use. As an introductory gun for the range it seems like it has a lot of features that I think would confuse the new shooter, and for a light bush gun the features that make it nice for new shooters (oversized controls, etc) may be undesirable. My suggestion would be to make this prototype to test both theories, but eventually separate the two into a separate system, dividing the features based on their tested abilities.

The other confusion I have is that if the idea is to teach shooters who will eventually move onto other guns, it seems like your effort should be to design the manual of arms to be as universal as possible, not as different as possible, how will they learn to operate an ar15 if they trained on a gun that did everything for them?

Unless your intention is to create the next Ak-47, or a battle/survival rifle that can be used effectively with little training, in which case your idiot proof features are on the right track.

I do applaud your efforts though as I only just this weekend was assisting my gf on the range. I've taken her a couple times before, but it had been a while. I was proud she remembered all her safety rules, but got confused with controls on my pistol and .22 rifle, especially with releasing the bolt.


In conclusion I'm very interested, please take my suggestions for what they are, and I look forward to getting some of my own confusions or biases cleared up.

barnbwt
May 6, 2014, 12:38 AM
"The most interesting part of this is the automatic ejection feature if it was simple enough and worked well, because it could be an interesting or even very effective solution for ambidextrous use during tactical work, which most ambi rifles lack (for example an aug or tavor though ejection can be switched, isn't automatic which would benefit off hand shooting)."
When I first had the idea, that was kind of my reaction as well; "man would that ever be cool if you could get it to work :cool:." And that's pretty much the only reason I'm pursuing it; don't want to give up too easy if the reward could be a really neat and unique feature that hasn't been tried before (I think). As far as switchable ejection, I think the Beretta ARX has a really cool concept in that their bolt has two opposed extractors, and shoving the (needle-like) charging handle through the bolt body to the other side deactivates one of them and makes it an ejector instead. I think pushing the bolt handle through the gun is all that's required to swap left/right. My thought was you could take advantage of the asymmetric nature of a right vs. left hand shooter to make the swap automatically.

The rifle is not intended for 'new shooters' so much as for introducing shooters to semi-auto 'assault weapons' and the notion of home built firearms, though the recoil/blast will be mild enough that I'd be confident newbies wouldn't find it too obnoxious. So it's not like they won't know what safeties are or anything ;) (bolt action 22 to start with, as always)

The rifle is really a hybrid of a pistol and a rifle, in pretty much all aspects. As we all know, pistols actually have more controls than rifles (except perhaps 5-selector-option H&K's :p) and have arguably more refined ergonomics specifically developed to make bringing the guns from an inert to operative position as fast/easy as possible. That aspect of pistols, I think has real benefits to offer a rifle platform. I think the ergonomic stability and control of rifles has enormous benefits over pistols (along with having enough room for a practical gas operated system). That is the motivation for 'automatic' safeties and controls, more than anything. I think it's an interesting notion that I haven't seen tried in rifles (I think one or two SMGs had grip safeties other than the terrible on the Uzi, but that's it) so I'd like to give it a shot and see if it's actually useful. The manual safety is really there as a fallback, since I don't think any grip safety location is protected enough that I'd be comfortable with a cocked rifle bouncing around on a sling or whatever. A manual safety that must be deactivated to grip the rifle properly would largely serve the same purpose but wouldn't be as 'unique' :D

"more buttons and features than a new shooter would know what to do with"
The point is to find a way to add them so the shooter doesn't have to think about what to do with them, like the grip safety on a 1911 (it probably doesn't confuse as many shooters as the manual safety lever does ;) )

"My suggestion would be to make this prototype to test both theories, but eventually separate the two into a separate system, dividing the features based on their tested abilities."
Efficiency of movement; I've already got a year of 'work' into this one to get it to this point, so at the rate I'm going I'll be an old man before test fire :D (j/k, got distracted by parts kit mania last year; this year will be much more focused). I've got a ton of gun ideas (doesn't everybody?) so I'll definitely be watching for what features are nice for what purposes and why, as well as the opposite, when I go to lay out those concepts.

"The other confusion I have is that if the idea is to teach shooters who will eventually move onto other guns, it seems like your effort should be to design the manual of arms to be as universal as possible, not as different as possible, how will they learn to operate an ar15 if they trained on a gun that did everything for them?"
Yeah, but I think other platforms' controls suck :neener:. Kidding again, of course. I just think most guns' foibles like forward assists, lack of bolt hold open, bad safety locations, (scary) moving charging handles, and lack of ambidexterity make many of the common guns unintuitive or intimidating to unfamiliar shooters. Took me an embarrassing number of seconds to figure out the T handle on the first AR I handled, I've never liked many features of the AK controls, and even my beloved VZ58 has a safety and mag release that could've used some work. And on all of these, there is still a lot of conscious thought that has to go into making sure the gun is safe/not safe, making sure the new mag's rounds were chambered, etc.

The manual controls are great when you are familiar with them, but they get in the way while you're on the learning curve, so a gun that dispenses with a few pitfalls would be nice. I look at it as a manual vs. automatic transmission; a manual can do a lot of things an auto can't, but it's a lot easier to learn to drive on an automatic, then learn to drive the manual once driving's no longer a challenge/distraction.

"For absolute ambidexterity in ejection consider using a system like the FS2000. There is a ejection tube that parallels the barrel. Empty cartridges are placed in the ejection tube and drop out near the front of the forearm, out of the way."
No way in heck am I even gonna try to duplicate what FNH dumped multi-national corporation R&D big-money into to get working :D. I agree forward eject is a definite winner, but the 1x1" tube that contains all my rifle's bits just doesn't have room, so a completely separate tube on top/alongside the sight line would have to be added. Unless that extra weight/volume was doing something else important, I just don't think it'd be the most efficient use of steel.

"Grip safeties and firing pin blocks are generally overkill for long arms. Each thing you add increases complexity and cost while reducing reliablity."
If this thing's reliable, I'll be laughing the rest of my life. I fully expect it to be a finicky, obnoxious mess, much like most prototypes :D. The gun is supposed to rival a pistol in its handiness and packability, so the ability to be carried/sheathed cocked and locked like a pistol would be seemed a very useful feature that is somewhat lacking on modern rifles (a very conscious and/or difficult or dexterous deactivation is universally needed to put a rifle on safe, since you really don't want soldiers going loud too easily --at least that's the theory :p)

"Cool idea overall, but I would never own a rifle with a grip safety, and would certainly never use it to teach new shooters."
Eh, lotta folks say the same about pistols. To each their own. I think safety activation is pretty much automatic/unconscious for experienced users, so why not make the transition from conscious effort to automation as seamless as possible?

"For classic field position type shooting, like we teach at Appleseed, we teach that the only part of the trigger hand that is putting pressure on the grip is the bottom 3 fingers, pulling the grip straight to the rear to keep the stock in the shoulder pocket. Furthermore, we frequently have shooters rotate their hand around the stock so their thumb isn't wrapped around the "wrist" of the stock, to keep their trigger finger from "dragging wood." I wouldn't want to encourage the type of gripping that would be necessary to actuate a grip safety on a rifle."
Thanks for the detail on grip! This is what I'm after, since I'm pretty much the opposite of a trained shooter, and know only the bad habits I've developed. The goal is not to create an obnoxious, in the way grip safety that precludes a proper or natural grip; but one that works in tandem with the shooter. At the risk of praising Gaston Glock, I would say a trigger safety would be a pretty much universal place to locate a safety lever needed to fire a gun, but I also think that that would be stupid here since I'm trying to maintain a quality trigger feel :D. I wonder if the portion of the stock where the lower fingers grip? The trick is finding part of the shooting grip that is not the same on each side, which is why I thought that placing something alongside the trigger finger, thumb, or palm might be a contender. I even thought about making the cheek-piece rock side to side to perform the function, but that would make hip firing really difficult (tee-hee, 'cheek-piece' :rolleyes:) and I definitely want to be at least able to Rambo off a drum like an idiot once a year on my birthday.

"Until then, I don't think this rifle is intended "for classic field position type shooting""
Yeah, it's really meant more for informal plinking or mucking around; the rifle you wish you had when you were a kid :D. I certainly don't want to prevent any positions from being tried, but I also know that the very short stock and forearm will prevent certain maneuvers, and that if anything more than cut-down 5-round magazine is used that prone is a fore-gone conclusion. That's a large reason for the M1 Carbine sights (that and they're cool doohickeys); they aren't really nice enough or stable enough for fine precision past 100 yards or so, I'd think, but are very fast and accurate enough for larger targets at the distance the cartridges this gun will see could reach to.

"I also have to wonder if barnbwt's grip safety design will cause the same number of problems with accuracy as the grip safety on a Colt Gold Cup. That number being 0. If done right, barnbwt's grip safety may have the same number."
That's the plan, if you guys can provide the inspiration :cool:. I certainly don't want features detracting from the gun's capabilities or shooting experience. I'm also not yet convinced that the features I've put forth by necessity do. I think they just need to be ergonomically refined (remember when charging handles were cranks, mags stuck out the top, and sights were offset and adjusted with a 4" hand wheel?)

TCB

barnbwt
May 6, 2014, 12:53 AM
And now an update on the project (hope I'm not too tired after that last reply :p)

http://i1159.photobucket.com/albums/p630/barnbwt/FCG_zps5fa44626.gif
Please forgive my hideously-stained fingers (filing/sanding aluminum and sanding off crummy black paint on the STGW57 ;)). I'm just demonstrating how the trigger pull and sear friction balance each other at the end of the first stage, before slight additional force pulls the trigger sear off the hammer bent. Even with that crummy piano wire spring with only 90deg of travel, that hammer beat the crap out of my knuckle when it got in the way --definitely would kill primers even in the current configuration (but I doubt the aluminum hammer face or sear ledges would last long :p)

I made up an aluminum proof of concept of the trigger mechanism, and it's pretty much a success (but different from any trigger I've shot). Very light takeup, and very light and abrupt break, but with a caveat; the first stage is pulled back and down, the second stage is pulled straight back. Unlike other two-stage triggers, the user, and not springs, determine where the break occurs (so technique is key). The two stages are very similar in weight, but the first only rotates the trigger, while the second actually slides it off the sear. That difference between rotation and sliding is what the user's finger must do for the best pull, otherwise they will over/under rotate the tail of the trigger from the recess and be rewarded with a rough break with little takeup (under rotation case) and a too-long takeup with inconsistent break at the very end (over rotation case). The hammer falls regardless how the trigger is pulled, but shooter nuance affects the feel greatly (so maybe not the best bet for beginners :o)

The little sheet metal piece is a stand in for the disconnector, whose exact form I haven't yet settled on. It will function roughly as shown no matter what, though.

I still think it's hilarious that a hack saw/file formed aluminum hammer and trigger with improvised heavy (but too pliable) piano wire springs with hand-roughed sears laid onto wood could have a ~3lb smooth/consistent takeup of 1/8", and a smooth ~4lb break (and with a whopping .03" of sear engagement, too). I can only imagine that quality 4130 steel and more than 2 hours of effort would yield even better results.

TCB

leadcounsel
May 6, 2014, 03:39 AM
I didn't wade through all of the above posts, so my apologies.

Who is your market? Beginners? Beginners don't buy rifles to learn on. Someone who already owns a rifle teaches them on whatever is available. Then the beginner, after about 1 day at the range, is no longer a beginner, and quickly graduates to novice.

Now if you were making the PPSh41 or whatever that 762x25 rifle was, and making it affordable and historically accurate, I'd be on board with ordering one to shoot up my horde of ammo!

But I just don't see a market for a beginner rifle like this.

I'm not trying to shoot down any creative minds or inventors... but I must honestly ask what does this design do that dozens, perhaps hundreds, of already existing designs don't already do... we're talking about designs that are tried and true, available today (not vaporware that might be on the market in 5 years, from a startup company that may not be able to fix problems, warranty, etc)?

The gun design market is simply saturated and gun prices today are super low... and there are so many manufacturers of guns...

Frankly if you're looking to make an easy buck, make springs and small metal parts like hammers and guide rods and slide stops and ejectors for all of the guns of yesterday for which those parts are nay-impossible to find.

Simple machining of already existing parts and a huge market. Look at Numrich. Everything is sold out!

I just bought an old pistol and spent 3 days hunting for a necessary part that nobody makes anymore.

Back on track to the OP. The gun may or may not work, I have no clue. But why not just go buy an SKS, Ruger mini-14, M1 Carbine, Ruger 10/22, Keltecs, Savages, .410 shotguns, or any number of $500 rifles...

Not trying to discourage, but what significant innovation does this offer to sell itself...? And to what market?

barnbwt
May 6, 2014, 08:57 AM
"Who is your market?"
Me. :D The 'newbie' use I'm talking about is demonstration, for which easy and intuitive controls would be a must so they can focus on fun shooting rather than tedious technique. Features I think would also be useful in a pack plinker.

"The gun design market is simply saturated and gun prices today are super low... and there are so many manufacturers of guns..."
And more every day, innovating, because there's actually a lot of demand for better designs (again, not that marketing is my goal)

"Frankly if you're looking to make an easy buck"
I'd make stupid AR gadgets like a selector with three positions (safe, semi, semi) so the ninjas with three labels on their lower could 'use' them :). Or I'd make PPSH trunnions for 50$ a pop and undercut everyone.

"But why not just go buy an SKS, Ruger mini-14, M1 Carbine, Ruger 10/22, Keltecs, Savages, .410 shotguns, or any number of $500 rifles..."
Because that isn't an option (please read the thread). I don't have some pipe dream about being the next Kel Tec or whatever; I actually plan on building a functional gun. Far more exciting.

"Not trying to discourage, but what significant innovation does this offer "
Read the thread. The cartridge, action, layout, controls, and intended role are quite unique from anything available (with a possible exception being the M1 carbine --maybe)

TCB

Nom de Forum
May 6, 2014, 10:44 AM
Not that barnbwt is much concerned about marketing, but I think there is definitely a market for the unusual, especially if it is very functional. "SKS, Ruger mini-14, M1 Carbine, Ruger 10/22, Keltecs, Savages, .410 shotguns or any number of $500 rifles" - Boring :(. Some people like to step away from the mundane to have fun. barnbwt I am ready to be put on the wait list as soon you have a well functioning design and are ready to build more. :D

barnbwt
May 6, 2014, 11:49 PM
I scribed out the cut lines on my receiver tube today (which I suppose makes it a "firearm" in the eyes of the ATF per the EP Armory ruling :rolleyes:) to get a real-world feel for the size of the thing. CAD is extremely misleading with regards to perceived size, since every detail you look at is approximately palm sized when you work on it zoomed in, so soon all the large and small parts grow & shrink in your mind's eye to be closer to the same size. This gun will make an M1 Carbine look/feel like a fat kid. It really is more of a 'machine pistol' than a carbine, the main body being a smidge longer than a Mini Uzi, and smaller in all other dimensions than many service pistols (without a mag or stock, obviously). But for the long barrel and stock, it would have the same profile as a sawn-off single shot 12ga.

The foregrip is short, but only because the full-size stock I currently have to mock up with (14" LOP) is disproportionately long and rakes the weak hand grip angle back to about 45degrees. A short 12 or even 10 inch LOP would bring the rifle in closer and get the wrist closer to 90 degrees out from the barrel. The short LOP will also get the carbine square in front of the shooter like how many do their M4s and other low-recoiling rifles (this has the benefit of seemingly making the shooting hand grip more asymmetric and less variable; you pretty much have to put your thumb on the strong side to be comfortable on a straight stock, and if I put the sights real low, you won't be able to use them if you wrap the thumb over the top)

I found there will be an immense temptation to wrap the thumb or fingers over the receiver, right were the gas vent will be (:evil:) along with a reciprocating bolt carrier through the lightening/vent cuts at the fore, so I need to come up with a clever means of discouraging that through non-painful ergonomic means. Perhaps an angled grip to move the hand back toward the magwell (or just a taller forestock to drop the hand down), or a very short vertical foregrip that would be gripped by the thumb and one or two other fingers (the gun is so small and light that this might be more practical than I'd think at first glance). Maybe even a 'sabre handle' flat loop below the barrel that the fingers curl into and the thumb wraps around the front of.

As far as cost, I'm one 30$ 308cal demill Winchester 100 takeoff barrel (Numrich), 150$ in 4130 tubing (and we wonder why no one builds stuff in America anymore :rolleyes:), a 10$ share of 4130 bar for the bolt/flaps, 50$ for the PPSH mag and magwell adapter, and probably another 50$ in 4130 for the FCG parts, lower receiver structure, and pins/springs. The stock, if you really want to count it, is probably 30$, but it came from my parts pile so it's free to me. Minus labor, cuz I'm having the time of my life designing/building this, it probably comes to 400$ or so if I don't waste money on dead-ends along the way (yeah right).

In a manufacturing setting, the receiver could be completed in two jigged positions in minutes on a light CNC machine, and the two telescoping receiver tubes would then be oven brazed or welded to each other. The bolt would take longer being billet, but is probably a 3 position part (flaps are 2 position parts). I also suspect materials costs would be less than half with bulk/contract agreements that eliminate shipping additions. In short, I think the gun could probably be made for 300$ or so, which is about as cheap as you can build anything that isn't Zamak or cranked out by the billions on mass-production equipment.

TCB

leadcounsel
May 7, 2014, 01:55 AM
Best of luck to any entrepreneur.

However, moving the selector switch and the angle of a rifle, and a few other changes for the sake of changes wouldn't make me a consumer...

As I mentioned, there are a plethora of tried-and-true designs and I've rarely thought about ditching one of those because of the angle of the grip, or location/design of the safety. *Could* they be marginally better... sure, I suppose.

But that misses the point. The lions share of the rifle market are AR15s, AK47s, Ruger 10/22s, Bolt rifles, SKS, and Mini-14s/30s, pumpguns, lever actions, etc.

A novice is being dis-serviced by shielding them from the operations of the majority of the rifles by learning on some unique proprietary design that shares nothing in common with the above referenced long guns.

It would frankly be better to teach a novice on a gun they might actually encounter or purchase in the real world, rather than some unique gadget they may never see again.

Say you get to spend 5 hours with a novice to teach them how to use a long gun. You'd be better off grabbing a handful of the most common and diversified long guns to teach them how to operate - say an AR15, a pump gun, a lever action, a bolt action and an AK47. Spent a solid hour with them on each platform, and they would be competent with the overwhelming majority of rifles found in America. But if it can be only 'one' rifle, again, I'd say take one from the above list, not some unicorn ...

Just my 2 cents.

barnbwt
May 7, 2014, 09:30 AM
"I have a number of features devised to make things easier and more intuitive for them, which I'll list below in case you'd like to suggest/add things. (Please refrain from turning it into an AR ;))"

I would consider AR/AK features, but they'd have to earn their spot; there's no sane reason a designer with free reign would choose an AK safety, or AR charging handle, for example.

TCB

kayak-man
May 7, 2014, 09:56 AM
I've got a few thoughts, no idea how mechanically feasible they are, just throwing this out there:

-For ambi brass ejection, would it work to have the brass ejected straight up, and have a curved piece of metal that you can rotate to deflect it either left or right?

- charging handle on the forend is interesting, but I feel like it may not give the best leverage for a new/ unfamiliar shooter, and to me, it just seems awkward. maybe something like an FAL style folding charging handle on the side would be a little more ergonomic, and out of the way? If you could find a way to mimic the tip-up barrel of those little Berretta autoloaders, that would be sweet!

- I'm assuming you want to keep it in a rifle or subgun caliber, but what about 9mm?

Honestly, I don't really know what I'm talking about, and if you decide that my input was complete rubbish, that's fine by me. Either way, I'm super excited to see what you end up with.

barnbwt
May 7, 2014, 11:00 PM
Thanks for the input, Kayak. Feasible or no, they are ideas from outside my head and therefore appreciated :cool:

-The shell deflector is my fall back (as is simple vertical-forward ejection), but it seems like it'd be rough on brass, which is a really bad thing for reloadable tok brass (as well as for cut down 223 brass)

-I, too, think a forward handle would be nice (though I personally don't think a FAL or G3 handle is all that small even folded; just not obnoxious), but I really just don't see a place to put it. Unlike those guns, there is no parallel tube for the cocking tube or gas piston on my rifle; the piston is concentric to the barrel. That means my cocking options are limited to hooking onto the carrier right around the barrel. The sights block the top plane, and I'd like to keep the sides as clean and snag free as possible (if at all possible). Hence my thinking of putting it on the bottom plane. Side or top cocking would work if I could do it in an extremely low profile manner that was also still somehow easy to access. I at least have more room to work with on the bottom from the foregrip wrapping around everything. I'm even looking into whether a levered foregrip (think pellet rifle) would make enough bolt carrier travel to work. The pump action idea seems the most practical for the time being (would be a bit weird to pump past the barrel on an SBR, though)

-9mm is a distinct possibility since it feeds from PPSH stick mags, but the locking system of the rifle is probably wasted on it; the mass of bolt/carrier alone are probably enough for a safe blowback (though it'd still be close on that count). With the right gas port, 9mm would likely have enough gas to cycle it, though. Hot 9mm Largo or another 'magnum' 9mm round would be a hoot, though.

-My barrel is actually a quick release type, with two large lugs that rotate to engage matching lugs in the receiver tube like a bolt action. The locking action actually tensions the barrel (and would improve accuracy on an SBR without an ant-eater nose) against the nose of the receiver. Kinda precludes a tip up design, unfortunately. A 'break action autoloader' is kind of a neat concept, though, and would seem to work for all fixed-barrel designs, so long as the receiver is laid out to accommodate it. My receiver, being a tube, just doesn't have the meat on the underside to keep everything together like a pistol frame does.

Here's a newer mockup picture, using the marked-up steel tube to show the relative size of the thing (barrel is positioned behind, not inside, the tube because it has not been turned down to the .58" OD I'll end up with). You can probably see the cut line 2" from the end of the tube, which would like up with the stock. You can also see the cut traces at the front of the butt stock. Most importantly, see the 1" square tubing that makes up the core of the receiver; not a whole lot of room for stuff in there. As I said earlier, the current LOP is out of whack with the size of the gun; 13" is closer to long rifle size, so I'm thinking 10" is probably more fitting. The gun is basically sized like a toy gun, but can pack some pretty serious power when you start talking 10mm from a Shpagin drum or hot-rodded 7.62x25. The drum would cut a good 3" off the overall height (and add it to each side)

TCB

barnbwt
May 17, 2014, 02:31 PM
How's this for a possible solution to my grip safety/ejector selection switch;
-A flush-set button on the sides of the grip where one of the shooter's finger tip would depress it, but where their palm on the opposite side would not? I'm thinking the middle finger would be the best since it's the most dexterous after the index finger (and for good reason :D)

I've whittled down the Steyr stock quite a bit so it's not near as fat and straight as it was (deeper comb cut, smaller inside radius on the grip underside, and thinned the sides). Now, the middle finger just happens to lie pretty much on top of the holes for the sling-swivel Steyr stupidly installed on the side of the grip, originally. That's what gave me the idea.

Again, I would try for a button that only takes a pound or two to actuate; does that still sound like an awkward solution?

Hopefully I'll be able to cut metal on my receiver tube tomorrow, and the mockups can start looking better :D

TCB

Sol
May 17, 2014, 02:49 PM
The charging handle is reminiscent of a FAMAS or Clarion or whatever it is.
Except it's on the bottom not the top.

barnbwt
May 17, 2014, 04:24 PM
Early AR10's, too :D

TCB

barnbwt
May 27, 2014, 08:57 PM
Alrighty, I'm gonna try to do a slide-action foregrip in lieu of a protruding charging handle for the following reasons;

-Cleaner appearance/smaller profile
-Full protection of hands from hot gas (no slot for gas to blow through)
-Stronger mechanism (it's easy to add strong metallic rails for a slide to ride on; a narrow handle, not so much)
-Hidden small parts (dirt/debris)
-Short action throw (2.65" is short enough the motion would not be awkward)

Possible cons:
-Less movement for shooter forearm (there are benefits to both methodical and intuitive motions for charging, namely what the other hand might be unintentionally doing around the ejection port vs. how fast it takes to perform the operation)
-Moving the support hand toward the muzzle (and beyond it in an SBR format) seems less than desirable. If a careless shooter thrust his hand forward without enough grip to drag the grip with him, his hand would be forward of a live muzzle (unless I also incorporate a grip safety that would require a two-handed grip to utilize). This is mitigated by the action having a short 2.65" throw and lightweight springs

In any case, I think the cons are minor enough that I'm giving the slide action a shot. That raises some questions about function that I hope ya'll can help answer. The slide will be held to the rear when firing, but is thrust forward to latch onto the bolt carrier then pulled to the rear to cock the action where the slide automatically disengages.

-I want a positive catch holding the slide to the rear except when cocking. Would you prefer a finger-activated switch (probably on the front end) or something like pulling down on the foregrip itself to unlatch it for cocking?
-Would you like the slide motion to automatically lock the bolt back until the switch is released? I do plan on having a dedicated last-round-bolt-hold-open with manual de/activation so this might be redundant
-Even though there is no spring resisting the forward motion of the foregrip slide, does a smallish Schnauble-style fore-end swell seem sufficient to keep a weak hand from sliding forward into the line of fire? Is it even needed?
-Do you think a grip safety is needed, or at least a 'full back' safety, to prevent the gun from firing with the slide slightly forward (the returning bolt would snag the slide and snatch it from the shooter, and their fingers would be forward on an SBR muzzle)?

TCB

sawdeanz
May 30, 2014, 09:30 AM
Just wanted to let you know I'm still following. Can't wait to see videos if the action. I think the pump action is intuitive, why can't it just catch the bolt on the rear stroke instead of pushing it forward first?

barnbwt
May 30, 2014, 12:19 PM
Sliding forward first allows the action to be 2.65" shorter during firing :cool:. Lots of Czech heavy weapons cock this way, but using the pistol grip rather than a forearm.

TCB

barnbwt
May 30, 2014, 08:09 PM
Per some recommendations on another forum, the safety/selector lever layout will work thusly;
-Just by happenstance, the sling-swivel hole is right where my middle-finger tip rests
-I will run a flat, slightly-below flush lever from this hole around the front strap and around to the other hole on the far side of the stock
-This lever will effectively function as a finger groove, and will be pulled ~1/16" toward the shooter's strong side by their grip (assuming they grip between finger/palm like a normal person, and not finger/knuckle, which might prevent the lever from moving properly)
-The lever will position a piece inside the receiver that will cause one of the ejector pins to not be projected from the bolt face against the case head (not pressing the lever will fire both out, sending the case vertical as opposed to a FTE)
-The lever will also move a tab restraining the tail of the trigger (the recess block in the trigger animation) and enable the 1-2 stage trigger (finger pull technique determines specific trigger let-off feel)

TCB

barnbwt
May 31, 2014, 11:01 PM
The journey of a thousand miles, begins with a single step...or CNC stepping servo, to be specific :D

Got the upper-side cuts and locking recesses cut into the inner receiver tube (the main body of the gun). Eventually a "saddle" of larger tubing will slide over the recess area and be welded/brazed to bridge the receiver. I'll have to put together an updated mockup of the parts I've got so far

So far, it looks like the CAD :). Next step is getting the bolt design finished up, so those parts can be made/fitted to the tube as it is. At this point I'm thinking I'll do the twin-ejector pin concept since the duplicate parts are at least easier to make in that configuration.

Since I have also gotten the stock to roughly the shape I want for this, I will mark out several locations for the grip safety levers along with my hand position for your perusal.

TCB

barnbwt
June 1, 2014, 08:41 PM
Here's the latest 'mockup of a mockup' using the stocks, receiver tube, and M1 Carbine sights.

I plan on cutting the stock another inch or so closer to the stamped markings, not because the LOP is long so much as the gun seems really out of proportion the way it is. I'll hold off until the barrel's on though, since that will probably even things out. Making the buttplate aluminum rather than the factory steel skull-stomper will likely help as well.

Phase Next will consist of getting the bolt assembly done, and I also need to look into the dynamics of the piston design to ensure I'll have enough gas to cook with (there's direct impingement AR uppers in 7.62x25 out there, so I'm confident it's possible, just rather close to the edge of what's possible ;))

TCB

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