wanting to design a new pistol/pdw

[justin22885]

as ive discussed a rifle design im working on in the rifle section, theres this other project ive started, it involves designing a new pistol designed to shoot some of the longer autoloading cartridges.. like 5.7x28, 4.6x30 (if you can even get them), .357 auto mag, .30 carbine, etc

so what im looking to desgin is a pistol and a PDW.. perhaps two separate designs, or perhaps a pistol that can easily take a longer barrel, stock, and forearm.. or like some 1911 and glock kits, an entirely separate upper to fit the same frame

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so im going to design a double-stack magazine around say a chopped .223 case, so anything sharing a base diameter with the .223 or smaller can easily fit the magazines and work on this setup.. i think though this will probably use more of the luger grip angle.. reason for this is if you hold the luger grip vertically, the cartridges are stacked at an angle.. this allows longer cases in a shorter, more comfortable grip, and of course itll be double-stack

i want to extract as much performance of these smaller cartridges (compared to .223) as i can and make the firearm as light as i can so i think i will avoid gas systems.. also delayed blowbacks release a large amounts of higher pressured gasses into the receiver that i think we could focus more on pushing the bullet down the barrel.. this leads me to think some type of short-recoil system to be best

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well since this has to be accurate, i do not want a tilting barrel but instead one that recoils straight back for about a quarter inch.. so my idea is to use an easy to unlock locking system, that unlocks in more of a linear fashion (as upposed to rotating bolts).. im leaning towards roller-locked short-recoil much like what the CZ-52 uses

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i can have the barrel and slide recoil together as a single unit, both stop after a quarter inch and the bolt inside continues on to unlock, extract, and rechamber.. this pistol would end up looking something more like a browning mark 3.. open sights or a pistol red dot could be mounted on top and i could make provisions for quickly changing barrel length, and adding or removing a stock and forearm to the frame portion

or what i could do is just have the barrel recoil, stock could be mounted directly to the end of the tubular upper, and a barrel assembly including a forearm, barrel, and inside the front of the forearm could be the stop that supports and holds the barrel when forward.. the block responsible for the barrel returning to zero.. so this would likely be easier to convert to a carbine

or again my third option is to design a completely different pistol and a completely different carbine both designed to fire the same cartridges, take the same barrels, and use the same magazines in the grip.. the carbine/pdw could end up being something more like a cross between an MP7 and a CZ-52 while the pistol would resemble something more along the lines of a ruger MKIII, but double stack, larger, and completely different action (MKIII is direct blowback i believe)

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so, what do you think? any ideas or comments?

 

[barnbwt]

The CZ52, properly designed, would have been a lot wider than it is. The current design leaves the chamber much thinner than it really should be (still, few have issues with this, and metal variance is a far bigger factor in failure).

Were I to pursue a roller locked barrel...
First off, the locking force needs to go out the sides, as opposed to vertically, since the slide rails just won't tolerate it. That means your slide walls need to be strong enough to take a good bit of lateral load. The combination of beefy slide walls and the roller's thickness on either side of the chamber mean you're headed for a fat handgun . So I'd see if you could relocate the rollers out of the slide entirely, and get them down into the frame somehow. Use a big underlug/feed ramp/rib on the barrel to mill the locking features in. Cut a slot through perpendicularly through it for the rollers to move side to side, and cut a narrow slot through the middle of its length for frame-mounted rib to pass through. The rib initially sits between the rollers, forcing them out where they will engage the slide (I'd also use a slide rail design like a modern CZ's where the lower frame supports the slide walls against splaying outward). As the slide/barrel recoil, the rollers reach the end of the rib, and fall toward the center of the slide, decoupling the slide and barrel. Functions just like a CZ52, but far simpler in construction (no separate locking piece to be tensioned).

Personally, I think it'd be interesting to experiment with a roller lock that allowed a tiny amount of initial, heavily-leveraged blowback, so you get some of the benefit of damped recoil impulse

TCB

 

[WestKentucky]

You could try the beretta 92 action except with a bolt moving inside what is a beretta slide. Short recoil of barrel driving back a bolt unit could easily be as smooth as the beretta.

 

[justin22885]

well my intention wasnt to use the cz52 action exactly.. ive even considered going with the luger toggle-lock as well, incredibly simple in principal.. i just dont think it would be all that great for this project because it would force the sights to be forward of the action, or the rear sight to be part of the toggle lock mechanism which wouldnt be very accurate

another interesting design im studying that locks on the bottom, no tilting barrel is the C-96 mauser.. it as a piece attached to the barrel/slide assembly that has grooves that lock to the bottom of the bolt.. when the bolt and barrel assembly slide back, this block drops unlocking the the two.. similar to how a standard handgun may function, this just using a separate locking piece so the barrel can just travel rearward only and it drops into the frame

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to answer some of these other question.. how much accuracy do we need here? the 1941 johnson rifle, judging by accuracy results from people who own them, they were getting around 2" groups at 100 yards, do we need more than this for a pistol/carbine/pdw? this determines if the barrel should recoil independently of a slide, or if a slide should be used to mount optics and sights to? and if the barrel/slide recoil together, would a pistol red dot sight be suitable for the added accuracy and range capable in some of these PDW calibers?

 

[justin22885]

ive been doing a little work on it.. trying to stick with a basic tubular upper similar to the MKIII.. and im thinking if i can get the C96 style block to work in this pistol it could allow for incredibly simple locking and manufacturing.. but im going to need to design this to use a striker-fired mechanism

now.. i have a complete 3D model representation of a glock 17 pistol.. what if i designed this to use common aftermarket glock trigger parts?

 

[WestKentucky]

Either glock trigger or any other common trigger parts would be nice. Another nice bit would be a safety that could or could not be installed so that people can't use that argument to justify their choice to buy/build or not.

 

[Kiln]

Somebody needs to build a semi auto pistol that loads in front of the grip like the Tec-9 that actually works. I doubt it'd be hard to do this and surpass the quality of the Tec given the advancements in CNC machining technology.

Unfortunately there are zero manufacturers building guns like this right now and it is too bad because they're perfect for home defense. You can use 30 round mags with them and their size makes them easier to hang on to plus they won't make you completely deaf after 4-5 shots inside your house if somebody breaks in like the PAP or Kel Tec PLR16.

 

[justin22885]

Somebody needs to build a semi auto pistol that loads in front of the grip like the Tec-9 that actually works. I doubt it'd be hard to do this and surpass the quality of the Tec given the advancements in CNC machining technology.

Unfortunately there are zero manufacturers building guns like this right now and it is too bad because they're perfect for home defense. You can use 30 round mags with them and their size makes them easier to hang on to plus they won't make you completely deaf after 4-5 shots inside your house if somebody breaks in like the PAP or Kel Tec PLR16.

but you could get 30 round magazines for a glock, so what purpose would having a magazine in the front serve but to make the pistol heavier, longer, and more front heavy?

 

[barnbwt]

"I doubt it'd be hard to do this and surpass the quality of the Tec given the advancements in CNC machining technology."
All you'd have to do is add metallic rails for the bolt to ride on instead of plastic (brilliant decision, whoever designed the Tec 9 ) and you would fix about 2/3rds of the issues. Run it on Uzi mags and solve the remainder

"but you could get 30 round magazines for a glock, so what purpose would having a magazine in the front serve but to make the pistol heavier, longer, and more front heavy?"
I thought you were looking into more powerful, longer pistol rounds? Anything longer than 45 will draw howls of protest from most shooters for making the grip longer (and even raking the mag back as far as is comfortable can only do so much). The other major benefit of a forward mag is you can use curved magazines and assorted mag angles, and even drums if you wish. Uzi and Suomi mags are both good to go (the Suomi is possibly the best ever made) and dirt cheap as far as steel mags are concerned. If you are dead set on using pistol mags, it makes sense to put them in a gripwell, since that's what their design already compromised for.

Another benefit is that moving the mag forward allows for a much more compact FCG module set right behind it, and also gives you much more room for the locking piece you'll need to set under the bolt for a C96 action without going past the grip. I personally think it's a very cool concept.

Probably larger than you are looking for, but it's been a dream of mine to make a piston-op, bufferless AR pistol (sort of like the PLR) that's tweaked externally to look like a scaled-up Bolo; broomhandle grips, muzzle front sight and tangent rear, a cut-down T-handle in the back, the works . I'd start with a 80%, chop off the buffer ring and slab the sides, then finish the lower as usual. The upper would obviously be something more involved than that, but possibly just a very short piston conversion housed in a box-tube.

TCB

 

[justin22885]

there are many handguns with longer cartridges in the grip.. desert eagle, fn five-seven, the HK MP7 has a grip magazine and these are all for the most part vertical magazines.. add to that the luger p08/ruger MKIII grip angle and it would make the grip even more comfortable.. and id like the pistol version to this project, whether its merely extended for a carbine or uses a completely separate firearm for the short carbine role, i still want the pistol version to be a light, concealable duty style pistol

 

[Kiln]

"I doubt it'd be hard to do this and surpass the quality of the Tec given the advancements in CNC machining technology."
All you'd have to do is add metallic rails for the bolt to ride on instead of plastic (brilliant decision, whoever designed the Tec 9 ) and you would fix about 2/3rds of the issues. Run it on Uzi mags and solve the remainder

The Tec 9 was one of George Kellgren's earlier designs. Kellgren is a genius when it comes to firearm design and has created some pretty unique and amazingly popular guns despite failures (Tec9 when he was at Intratec and the failure to keep Grendel in business despite creating the forerunner to the PMR30 and P11) prior to the creation of Kel Tec.

 

[Kiln]

Also, to the OP's question:

Having the mag outside the grip makes it easier to hold on to by using the mag or mag well, without technically having a foregrip. Also, nobody makes one that I'm aware of these days in semi automatic format.

 

[justin22885]

i think if i was going to make a pistol with a forward magwell, id just modernize, update, and simplify the C96 mauser

 

[Drop45]

I can only imagine what John Moses Browning could have done if he had access to the interweb way back then.

 

[barnbwt]

Browning had it easier than we think; even stupid ideas like the Potato Digger were hailed as 'genius innovation'

"i think if i was going to make a pistol with a forward magwell, id just modernize, update, and simplify the C96 mauser"
I think you'd have your work cut out for you even if you so limited yourself. It's funny; the C96 isn't all they complicated just manufactured in quite possibly the most expensive and obnoxious ways conceivable. Use a screw-in barrel on the slide, and I think you'd drop like a third of the cost right there.

TCB

 

[justin22885]

well thats my point, ive been studying a 3D representation of the C96 mauser made from blueprints and i see a lot of areas where the design could be vastly simplified and costs to manufacture be greatly reduced.. and some more modern changes made.. for example, drop free removable magazines based on a commonly found, widely available double stack pistol magazine that can handle 10mm, 45acp, 7.62x25 and the likes.. or even longer like the 5.7x28

i might do something like that at some point.. i think i want a concealable handgun first, something like a ruger MKIII, but double-stack with a C96 style short-stroke system with the falling locking block and likely the glock FCG.. then design a separate submachine gun or carbine so i can make each one the best firearm it could be

at some point, i want to design my own cartridge.. which as it stands would be a .223 case cut to around 30mm length, necked down to .224 cal like it was before, push the shoulders forward for 45 degree shoulders, and essentially have a 5.7x28 style cartridge but base it off the larger, far, far more common .223 brass, giving it a greater case capacity and a lot more power.. designed to be used in only locked breach or delayed blowback designs we could maximize its energy output to its full potential and match .221 remington fireball in a cartridge small enough to chamber into a pistol

however.. this is something i must do separately to test loads.. i will probably just make a really inexpensive single-shot pistol for that purpose.. something i can easily change out barrels for to use whenever i feel like testing out a new cartridge.. until then i need to select an already available PDW cartridge to use in the pistol/PDW combo.. maybe .30 carbine since its around the same size as these other cartridge but far more widely available than the rest which will be handy when it comes time to testing prototypes

 

[barnbwt]

I'd seriously consider basing the frame off an AR15 forging, maybe with a shorter magwell (or not). Simply because there's lots of high-quality forged feedstock out there that would be far easier and cheaper to finish machine compared to doing everything from billet. Hopefully there's a way to do the action without requiring a steel frame, but that may likely be unavoidable.

If you do decide you need a steel frame, be sure to check out the Jack Squat's Flat Spot kit, which is probably the only 25$ AR 'blank' available, let alone a steel one. The only trick is some assembly is required (by which I mean all of it). But, the laminate/sheet construction allows for quite a bit of modification for various platforms, while maintaining the same convenient FCG and magazine geometry. A buddy of mine did his up without the buffer ring and plans build a monolithic square-tube piston upper as a faux CZ 805 BREN

A striker C96 should be easy, seeing how long the bolt body in the thing is. You'd have to make your locking piece slotted to clear the striker sear, though, which may or may not change some other things. You might have to make the locking piece and bolt body a bit wider inside the slide/frame to get the difference back.

"I will probably just make a really inexpensive single-shot pistol for that purpose.."
Save yourself some trouble and build it off a Mauser action (a new production one that didn't come on a rifle, obviously), then spend your time making barrels for it. That will be more than enough work/$ to keep you occupied

TCB

 

[justin22885]

i dont know about building stuff like this off a mauser action, then i have to bolt bolts, bolt faces, etc for the different calibers i may try out in the future.. for the most part a single-shot doesnt really need different bolt faces, nor bolts, just a single-action trigger i could probably "borrow" out of one of my colt revolvers, and a break open barrel

as for updating a C96, im not so sure id use a striker for that.. i dont know yet.. but using an AR-15 forging isnt a bad idea, with a smaller magwell. could use AR-15 grips and trigger groups, only problem is the ring on the back of the lower for the buffer tube is made for about a 1.5" piece of steel tubing which is far bigger than what you need for a pistol

at any rate though, thats the last thing on my priority, first i want a handgun that could work as a concealable duty pistol, as stated above would externally look very much like the ruger MKIII.. but may have a C96 type action, or possibly even a mauser toggle-lock if i think i could get a proper set of sights on it without the toggle lock interfering with the rear sight

 

[Old Scratch]

What about a slightly lengthened 1911 frame and mag to accomodate the 7.62x25?

Case capacity is great and you'd still be shooting a bullet of some mass. Many have objected to the Five-Seven because of the tiny bullet. There is some evidence the Russians/New Soviets are even returning to this caliber for its superior penetration in pistols.

Just a thought...

 

[F-111 John]

Having the mag outside the grip makes it easier to hold on to by using the mag or mag well, without technically having a foregrip. Also, nobody makes one that I'm aware of these days in semi automatic format.

I suppose AK and AR pistols don't count? Nor the Kel-Tec PLR-16? Or the Kriss Vector SDP?

 

[justin22885]

What about a slightly lengthened 1911 frame and mag to accomodate the 7.62x25?

Case capacity is great and you'd still be shooting a bullet of some mass. Many have objected to the Five-Seven because of the tiny bullet. There is some evidence the Russians/New Soviets are even returning to this caliber for its superior penetration in pistols.

Just a thought...

the 7.62x25 cartridge already fits in the 1911.. you can get barrels for this caliber but it requires you to have a 9mm extractor, ejector, firing pin, etc.. and i believe .38 super magazines

and the reasoning behind my idea is to get MORE power out of a pistol than what these more standard handgun cartridges provide.. but also more distance through a better ballistic coefficient out of a longer barrel

 

[justin22885]

are you guys worried your hands wont fit a pistol with a 40mm or so length cartridge?.. can you not handle a desert eagle? a FN five-seven?.. 40mm isnt bad at all for most people.. and if you angle the grip more itll be even more comfortable.. damn near every 45acp capable pistol is capable of firing 7.62x25 so it seems pointless to just design another one capable of doing the same thing of 30 other designs out there

 

[barnbwt]

"and the reasoning behind my idea is to get MORE power out of a pistol than what these more standard handgun cartridges provide"
Do be cognizant of the cost of doing too much with too little. If you haven't fired a five-seven, the recoil is low, but uniquely fast and sharp. Coupled with the muzzle flash and concussion, it is actually incredibly easy to develop a flinch on, same as with magnum revolvers shooting hot/fast loads. Continuing much further down the 'power' path to the point significant recoil also enters the scene, and you may be looking at a genuinely hard-to-shoot cartridge

"but also more distance through a better ballistic coefficient out of a longer barrel"
It sure sounds like you're describing the 5.7x28. Yeah, it's at the low end of pistol-caliber cartridges (sort of), but member Trent was apparently quite effective with it out to 200 and 300 yards in competition, which is not something you can say of (any?) of the similar platforms. Judging by the stubbier bullet, even 22TCM probably wouldn't do great that far out.

As far as Tokarev 1911's, I think they do require 38 Super frame/mags or slightly overall length (or both). I don't think a standard GI will work without thinning the front strap --totally going from memory here, though

TCB

 

[barnbwt]

"can you not handle a desert eagle? a FN five-seven?.. 40mm isnt bad at all for most people"
And yet that is exactly what most people complain about on those guns. Granted, the Eagle has whole lot more going on than just a big grip that makes it impractical. Even my CZ52 has a much-maligned grip length.

"and if you angle the grip more itll be even more comfortable"
There is a limit, and it is probably not much further beyond what you see from most pistol made today . Yes, you could use a Luger grip angle to shave off maybe 10% of the length, but it would be very diverged from modern ergonomics optimized for two-handed shooting --the highly-raked grip is best for fully extending the wrist with the arm in a duelists' stance, something that hasn't been in vogue going on 100 years. It would also pretty much relegate you to single stacks, since double stack mags work worse the greater the distance a feeding round must slide past the next one in the mag.

There's no silver bullet (well, except for those actual, silver bullets )

TCB

 

[Trent]

"but also more distance through a better ballistic coefficient out of a longer barrel"
It sure sounds like you're describing the 5.7x28. Yeah, it's at the low end of pistol-caliber cartridges (sort of), but member Trent was apparently quite effective with it out to 200 and 300 yards in competition, which is not something you can say of (any?) of the similar platforms. Judging by the stubbier bullet, even 22TCM probably wouldn't do great that far out.

6" group at 200 yards with the factory non-magnified optics.



I can put them reliably in to the black on an SR-1 target w/ SR-3C center at 300 yards (standard high power rapid fire prone target), but it's more challenging. The damn things are dropping like a meteor at that distance.