my rifle design


July 31, 2006, 08:51 PM
Some of you might remember me asking around for information on firearms design last summer.
As you all can guess, I'm interested in designing and building firearms.

I wanted to post a quick render of my new rifle design and ask for your opinions, suggestions and ideas.

I'd like to know if any of you know how I might go about having this rifle built, and/or selling/licensing the design to a manufacturing company.
Or if you have any suggestions related to that.

This isn't one of those "models" from them video games kids play these days.
This is a complete design, down to every pin and spring for the entire rifle.

This took me roughly a year, working on and off around school and whatnot.

I used Solidworks 2004 (.edu) for the design, and Maya for the render.

I also designed a bipod for it, and have a bunch of renders of the rifle sitting on said bipod, but right now I'm looking into building the bipod and maybe selling/licensing it separately.
As you might guess, the bipod's design could easily be "lifted" from a render like this.

The scope and scope mount are only here for the renders. I based the scope off of one of the Nightforce scopes, I couldn't actually measure a real one so I guesstimated it's dimensions using the photos and specs listed online.

That said, here's some quick specs on the rifle:

.408 Cheytac (or any cartridge of that class)
5 round detachable box magazine

Straight-pull bolt action
In the forward (closed) position, the bolt handle is ~2" behind trigger, so this isn't like the AMP DSR-1 rifle with the bolt really far back.

33" barrel (not including brake)
51" overall length (inlcuding brake)
15" length of pull (trigger to rear edge of stock)
14" of Picatinny rail (25MOA tilt in the renders shown)

the design's estimated weight is 30lbs. I know that's heavy, but the design is intentionally overbuilt at this point.
I think it can be cut down to ~25lbs fairly easily and I plan on doing that during the prototype stage.

center of gravity is 6" forward of the trigger, should move forward more with the ~5lb weight reduction.
(I figure having the center of gravity out on the barrel would improve stability for long range shooting)

As you might guess from looking at the render, I attempted to address the common problems bullpup rifles have, such as the poor trigger and excessive length of pull.

Image upload seems to be working

Forgot to mention, the thing is controlled feed and ejection too

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July 31, 2006, 09:32 PM
How (in general terms... I'm not trying to steal your idea :) ) does the action work? ie, Lockup mechanism.

July 31, 2006, 09:41 PM
30LBS :what: So we are talking about a crew served piece I see. :neener:

Looks good but a few questions?

Why a bullpup? It appears to be a precision rifle you are going for and the bullpup design is going to lead to a trigger that I don't believe will ever be up to precision standards.

Why all the rails? Again technically for a precision rifle you are not likely to hang too much crap off it and at 30lbs more stuff is not likely to be fun.

Just out of curiosity what is the niche you are attempting to fill?

Now all the criticism aside you have way more talent then I and have done a great job.

July 31, 2006, 10:07 PM
Personally, I'd like to see a scaled down Mauser chambered for the 7.62X39 Russian. 18-inch barrel...length of pull similar to the Ruger M-77 Youth Model...and about 5 pounds empty. Flip-up Aperture rear sight with 1/2 minute friction adjustments on windage and elevation, and a quarter rib...mounted low...from the Ruger #1 for a forward scope mount.

I ain't gonna hold my breath though...not "tactical" enough for the times.:cool:

July 31, 2006, 10:34 PM
Action/lockup resembles the AR-15, but I made changes to get the short length of pull with the bullpup design. Also other changes you might expect to get controlled feed/ejection and whatnot. Striker fired (no hammer) too, so it's got a light firing pin and fast lock time.

I'm looking at the Blaser 93 rifle's "petal" thing and thinking of designing a second version using a unique (or really unusual) action along those lines.

Yes, it's heavy...
Still, it can be reduced to 25lbs.
The 30lbs is the solidworks prediction using the aluminum/steel/carbon fiber densities and component shapes/volumes. This is without lightening cuts or other weight reduction techniques. Just haven't gotten to doing that yet. I figure I can take a break now that the base design is done.

The 14" of rail is integral to the top of the receiver. You can see all of it under the scope in the render.

From my reading online, it seems like precision rifle shooters were having some difficulty mounting night vision gear along with a large scope.

Some of the setups I've seen photo's of consisted of a scope with a NV unit in front of or behind it. Having rail lets the scope/nv mount without a goofy adapter or rail extension system.

I figure that I can get a longer barrel with the bullpup design for a improved muzzle velocity without making the rifle too unwieldy.
The bolt location is pretty much the same as on any normal rifle, so I don't think that's a problem.
The heavy barrel/brake puts the center of gravity out on the barrel where it should be.

I think that pretty much leaves trigger as the only downside.

My trigger is designed to be pretty simple.
It's adjustable, but obviously not as adjustable as those Anschutz target rifles. (Pull weight, sear engagement, overtravel).

The transfer bar and other internal parts are very sturdy, so they won't deflect deflect or anything.
I've also got a "zero travel" thing going with my current trigger design, but it should end up being dependant on how the sear and firing pin surfaces are cut on the actual rifle.

I don't want to get into my trigger design too much, but I think it should work out alright for a precision rifle.

I was originally designing this rifle for the .338 Lapua Magnum, but I saw the Cheytac Intervention rifle and figured I should up it to the .408 cartridge.

The .408 Cheytac cartridge is somewhere between the .338 Lapua and .50BMG as far as size/power goes.
I'm just kinda kicking this idea around, but one of the .408 wildcats, necked down to .338 might work pretty well. I may be mistaken, but I think I've read of them getting ~4000 fps with a 250 grain bullet.

Basically, I tried to design a intermediate size military precision rifle for 1000 - 2000 yard shooting.

Jim Watson
July 31, 2006, 10:36 PM

My curiosity runs with Jac's. Why and how a straight pull? You ain't shooting rapid fire with one of those things. I guess the rails are for night sights etc.

What are you calling "controlled feed and extraction?" AR and Blaser haven't got it.

Are you set up to produce a shootable prototype?
I suggest you do it in a common caliber so you don't have to worry about ammo cost and availability doing development and endurance testing.


How about a nice little CZ527? Pretty much the envelope you want but you'd have to flange up your own Scout sights.

July 31, 2006, 10:47 PM

That doesn't sound too difficult.
Most of the time this took me was due to inventing my own design, bolt assemblies and getting everything to fit right.

I've got a bunch of reasons, but I've never really been interested in "traditional" rifles.

July 31, 2006, 11:01 PM

I know the AR and Blaser don't have controlled feed and ejection, I modified the "AR" type bolt assembly so that the extractor always controls the round. My design calls for the extractor to grab the round as it feeds from the magazine.
Ejector is a unique system as far as I am aware, but it will not eject until you draw the bolt back past the magazine (where it would feed the next round). The ejctor doesn't apply pressure to the cartridge until this point, unlike the AR where the ejector applies a constant push to the cartridge.

As to straight pull, I figured "why not?"

This started as a hobby and something fun to do in my spare time. It was a "cost is no object" rifle designed to be something different.

I don't have the resources to build a shootable prototype at this time.
Yes, if I do get to building it, a .308 version would be easier to feed during testing.

August 1, 2006, 02:58 AM
Hey Tuner --

Have you seen the Enfield K before? Sounds close to what you want. :)

August 1, 2006, 04:19 AM
Turner--isn't that pretty close to the CZ 527?

August 1, 2006, 04:56 AM
boonie, that pup is serious! :what:

CRF, Straight pull - no monkeying around with bolt arc and very little chance of knocking it out of battery.

Is that brake knurled for ease of removal or some kind of flow-dynamics voodoo? :p
Sound suppressor easy to get on?

Looks like that carbon-fiber assembly can come off pretty easily to get at the barrel.
Ya think it'll withstand getting plunked down onto some field expedient support?
Free-floated? Quick-change barrel?

Good thinking on the rail.

I like how the adjustable cheek-piece blends with the reciever.
Nice grip bottom-plate too.

Hmm .. maybe a quick-detach brass catcher ..

I'm sure you already thought of fluting the barrel ..

I'm not too saavy on the manufacturing and patent aspects.
I gotta' crash. I'll see if I can think of anything helpful.

WTG boonie!

August 1, 2006, 11:58 PM
I figure that it's a "temporary" brake, so I just added the knurling so it would look pretty. A brake that takes a suppressor somehow would be ideal, but I figure that’s a ways away, once I move to a Title 2 state and have the resources to start building this.

Barrel is free floated, attaches like the Accuracy International barrels, so with good manufacturing it should be "swappable" like those rifles.

The handguard itself is pretty thick, the weak part is the attachment point. It uses AR style takedown pins for that, so it is easy to remove. I'm having trouble with my Solidworks license right now so I can't open it and check, but the receiver has something like 5/8" of aluminum around the pin for roughly 1 1/4" inches. The hanguard isn't as quite as thick where it hangs onto the pin. If this doesn't work, I can always try a different design.

As far as building this rifle, the difficult part will be the receiver. It's a fairly large piece of aluminum and will require a couple somewhat complex operations. It is all "buildable", but will be a real pain without a 4 axis CNC milling machine and some fancy lathe work.

I can't afford the raw materials at this point either.
You saw my AICS info request, I'm starting a project building something along those lines for another type of rifle, and the raw aluminum stock is going to run ~$150-$200. That's for something like a 2.25"x2.25"x30" piece of 7075 T6. (but at least I'm actually gonna build that soon, hopefully)

The receiver on this rifle design would run a bit larger than that, probably end up costing around $500 for the raw upper receiver aluminum stock. I'm sure "bulk" prices wouldn't be too bad. A hammer/forging setup probably would be cheaper per unit too, while removing a couple of the more difficult machining operations, but I obviously couldn't afford that kind of thing.

Aside from the upper receiver, all the other parts are pretty "buildable". Materials cost would be kind of high on a couple parts, but it shouldn't be too difficult to build with a regular milling machine and lathe setup. Heat treat might be difficult, I don't know much about that at this point.

I'm currently thinking of having a handful of parts prototyped, if its not too expensive, and building a "working model". With the prototyped receiver(s), it won't be firable, but it should cycle dummy rounds. I'm thinking that maybe I could interest someone in helping to build a couple rifles if I have a working model that I could show them. (even if its half scale)

Alternatively, I'll end up working on this rifle once I have the money and access to equipment to build the major parts. It would take a while though.

I'm probably going to end up building some simpler guns before I can start this. Maybe some single shot rifles and whatnot, but I will build this eventually.

August 2, 2006, 10:01 AM
That is impressive, to say the least. Even if it doesn't work out, you have still shown you have skills. Are you an ME ?

August 3, 2006, 08:09 PM
Yes, ME. Graduating this spring too. Still have to find a job....

Everyone else,
I want to thank all of you for your compliments, feedback and encouragement.

Hopefully I'll be back in a couple months with info on my current project. I'm going to be building this one, so I should have photos and not just design renders.

August 3, 2006, 09:59 PM
what's the margin of safety on the locking lugs?

Jim K
August 4, 2006, 12:04 AM
Let me see if my poor old mind can absorb this, but if I understand correctly, you don't have a rifle, or anything else. All you have is a bunch of pixels from a CAD program.

Now that is all very nice and CAD is great, but I don't think many companies are about to buy a design and set up to manufacture based solely on a design. I think you are going to have to spring for having the rifle made, in workable form, to see if it can even be made. That means full engineering drawings, not pictures.

You may or may not have enough to get a patent, but you will need to consult a patent attorney to see what to do next.

You also have to ask yourself what your rifle does (would do?) that current rifles in that class won't do. There is a limited market for high power sniper rifles, even for the military, and I would wonder if your rifle has features that make it enough superior to other rifles that someone would be willing to put out a whole lot of money to tool up to make it.

It is not powerful enough for use against serious armor, and too big for a squad sniper. It fits right into the same slot as the current batch of .50 BMG rifles without the advantage of using a known and widely available cartridge.

The straight pull action is interesting, and would seem to be an advantage, but has not been notably successful. On a sniper rifle it suffers from the same problem as a conventional turning bolt - the movement can lead to exposure of the sniper's position with possibly unfortunate results. A semi-auto action is a lot better.

Bull-pups also have not been great successes. Too many folks just don't like putting their faces right beside a potential bomb. A metal flaw can give the shooter a very bad case of acne.

So my advice is to get together enough bucks to 1) survey the market, disregarding most of the "gotta have one" comments, and 2) have a working model built.


August 5, 2006, 03:15 PM
Locking lug factor of safety is a little over 2 when only considering the "barrel extension". It's kind of like an AR-15 extension, but permanent to the receiver. The factor of safety will actually be higher because of a "reinforcing"/"bonding" thing I'm looking at doing with an unusually thick receiver around the extension. I don't believe that any current production rifles do anything like this. To be honest, I'm still looking into how to calculate the effect this will have on the FOS.
I used the pressure from a hot load running at 65kpsi for the calculations.


You're right and at this point, the design is little more than pixels on the computer.
I can make and print the engineering drawings or CNC machine code using Solidworks, so that wouldn't be a problem.

I have enough time on a milling machine and lathe to know that my design is buildable.
The main operation I'm worried about is a slot on the inside of the receiver that the bolt and bolt carrier use.
I've figured it can be done with a shaper, but I don't know a lot about those machines.

The worst case scenario for the slot is having it cut with a milling machine, where it can reach, and finishing it with a file in a jig of some sort.
It may not be fast, cheap or practical but it can be built.

The other difficult operations are things like the long hole that will need to be drilled through the receiver, and "aligning" the picatinny rail and rest of the receiver geometry to that.
Aside from the upper receiver, the rest of it is pretty simple machining.

As far as building it, I have always kinda thought that I would need a shooting prototype to get anyone interested in the rifle.
I'm glad that you've confirmed this for me. The people I've talked to before did not think this was necessary.
One of them (an engineer and shooter) looked at me like I was crazy when I brought up that I thought I should build a working rifle or at least a "working model" before trying to interest anyone.
He said "Just send a picture and your resume to Remington" and "you don't even need to build one to patent it".

I probably shouldn't bother with a model or prototyping, just build it as a hobby over a couple years and see what happens when I finish.
Or shelve it and work on simpler projects for a while.

My planning for this design never really involved a lot on the market or marketability of this rifle.

I started by making a CAD model and the engineering drawings for a STEN submachinegun for a school project.
I had fun with this and figured I should actually design something of my own. I've always been interested in long range shooting, so I figured I'd design a rifle.
I started by doing a lot of reading and research on rifles. I looked at the AI rifles, the Blaser rifle, the AMP DSR-1 and the Remchesters.
I decided on a straight-pull bullpup rifle for the .338 Lapua Magnum.

As I worked on my design, I ran across an article on the .408 Windrunner rifle. I think the article is over on the Sniper's Hide(or Central?) website.
It was about 2000 yard shooting with a .408 rifle. I looked into this some more, and found some articles about the rifle/cartridge.
I decided to switch the design to the .408 cartridge and I figured I'd design my rifle to be an "equivalent" to the Intervention with the same basic abilities but "better" (longer barrel, shorter overall length, same weight, better scope mounting, you get the idea).

My thoughts are that the .308 is good to ~800 yards with semi-auto rifles, and that the .338, .408 and .50 bolt rifles were good for the 800-2000 yard area.

Recently I have run into articles and arguments that the .408 isn't a good idea, for some of the reasons you've brought up. I'm also seeing a lot of skepticism about the .408 cartridge and the Cheytac company in general.

One of the 338 or .308 cartridges in this class may be a better choice.
A 250 or 200 grain projectile around 3750 to 4000fps would reduce drop, flight time and the wind effect.
I'm thinking that if the .408 has no practical anti-armor capability to speak of, the projectile weight/muzzle velocity tradeoff should be worth it.

After thinking about this a lot, I'll need to admit that my design is not very practical.
I didn't think about the cartridge selection and if this class (.338/.50 intermediate) would be a good idea.
I also didn't put enough thought into the market or niche this rifle would fill, and now that I think about it, the .408 is a pretty big cartridge to have in a bullpup rifle should it "kaboom".

I still want to build it, but it'll probably end up being more of a "curiosity" and one of a kind rifle than something practical.

Thanks for taking the time to respond, it's given me a lot to think about.

August 5, 2006, 10:37 PM
Why would placing material around the berrel extension increase the shear strength of the lugs?

August 6, 2006, 08:24 PM
Barrel extension in my design is permanent to the receiver, barrel change by screwing/unscrewing barrel.

Not sure how to describe it exactly.
Couple points.
In my FEA runs through Solidworks, the barrel extension fails with a combination of lugs shearing and "torquing" out the rear of the extension. Kinda as if you were pulling the thing inside out while pulling on the lugs.

In addition, from the cartridge's point of view as it feeds, the lugs are not completely visible, some of the area towards the base of the extension lugs is obscurbed by the receiver.

I've forgot what kind of fit it's called, but I figure if the extension is pressed in ("interference" fit?) and bonded ("glued") with a suitable bonding agent, the aluminum reciever will reinforce the extension.

Of course, I could be mistaken...

In any case, I figure the FOS of 2 should be alright on it's own...
Correct me if I'm wrong, but most firearms have a FOS between 2 and 3, right?

August 7, 2006, 10:36 PM
You might want to consider the 6.8 Remington SPC as it would reduce nessacary weight and take advantage of the longer barrel shorter stock. It is becoming more avalibe due to barrets new toy, one thing is are you prepared to deal with the stress that will be exerted laterally as the lands force the spin on the bullet? A second point people using anti-material weapons aka 50 cal, stay with what they trust as you really have to know how much damage it is going to do ahead of time as their is usually something you can't hit right next to what ever needs to go away. Cool idea and nice skills with the render. Oh as to getting the recevier milled many custom shops will make one and just charge you as if making a custom gun, but if they need to make new dies it is going to cost a fortune even if you have info for the CNC as the info always has to be tweaked for some reason or other. Oh and I have to leave with this last comment there is a reason why most people test fire the rifle from behind some sort of protection these days:)
good luck

August 8, 2006, 08:59 AM
Very, very cool...

Random ramblings, thoughts and brainstorming:

I THINK there would be a (small but) acceptable market for something like this. IF you could produce it, and sell it for say, $3000-3500. (Accuracy International (IIRC) gets about $4000 for a top-line rifle). Even at this price point, it could be fairly labor intensive, and still be profitable.

Stick with .338 LM, its kinda the long-range anti-personnel standard.

For God's sake, shorten the barrel...It's nice to think you can use a long barrel, because of the bullpup design, but its just not necessary, and might (because of barrel harmonics) actually hurt the accuracy. 28" including the MB would probably be plenty.

Get the weight down. I think you're being pessimistic about weight reduction. I think, with careful planning and design(and a shorter barrel), you could get this down to nearer 20 lbs., maybe less. I'd have to see more detail but I think it could be done. (My dad was a machinist, and I used to build race cars, and am an expert welder, so I have SOME experience with metalworking/fabrication).

You mention the complexity/size/difficulty of making the receiver. Could you possibly use a partially "built up" receiver to accomplish the same thing? (remembering that the locking lug area/mechanism is the most critical for strength, everything else is just there for feeding, etc.)

Bullpups. I love 'em. But the most serious problem with them is always the trigger. If you think you've got this worked out acceptably, great. But I would concentrate alot of effort in this area. Maybe an electro/mechanical mechanism? (Fly by wire!)

Again, just some ramblings. But its good to see someone (anyone!) that's interested in new firearms design.

August 8, 2006, 09:27 AM
dfaugh, looking at that design, he'd be lucky to get the first 10 made for anything less than $200k. I don't think a $4000 version is too likely.

Interesting design; perhaps some interior renderings? :)

August 8, 2006, 08:02 PM
No interior renders for now. :)

I've been playing with the upper receiver design, I think I've got a couple simplifications for it. I'll look into breaking the upper receiver down some more too. I was going with the "one piece upper" for improved rigidity between the sight rail and barrel (also more durable as a whole, I believe).

Basically, the "difficulty" in making the upper receiver is the length combined with all the necessary geometry. Drilling the hole through the receiver, and aligning the rest of the receiver to that, keeping runout down. Even a small fraction of an inch of misalignment will put the bullet off target at the ranges this rifle was intended for (1000-2000 yards).

Maybe it's not as difficult as I think, I'll need to look into it some more in any case.

If you're looking at the render, the upper receiver extends from the rear of the adjustable cheek piece up to the handguard, about 1.5" in front of the rail, where the color changes from grayish to black.

This is around 30" of aluminum.

If machined from 7075 stock (not forged or anything), the first step would be sticking it in a giant lathe or a specialized drilling machine and running a hole all the way through.
Then, the hole would get expanded from the front to back (and back to front), leaving a bottleneckish area on the inside.
After that, it could be run on a milling machine to cut the rail, lower receiver interface, magazine and trigger slots and any outside geometry. After this, there'd be some milling on the inside faces of the rear end, but easy to do on a normal milling machine. Then we'd need that slot cut on the inside of the rear half of the receiver.
After all this, we could mill (or even bandsaw) the sloped cutaway where the lower handguard attaches.
We'd also need to drill some holes through the receiver at some point, for the takedown pins and a couple other components, but that is relatively simple drill press type work.

The rest of the parts are pretty basic. Lower receiver is comparable to an AR, though longer and having different geometry.

The "comparison" rifle I used was the Cheytac Intervention, I think it weighs ~25lbs, so I picked that for my goal weight.

Barrel length was chosen because I figured that it would allow for a noticable muzzle velocity boost with the larger rifle cartridges, while still maintaining the handling and length of a traditional styled rifle of this class. As to barrel harmonics, I was actually thinking that it may work better with a larger diameter barrel, fluted to maintain the current weight.

Current barrel weighs 11lbs and is not fluted, muzzle brake shown is another ~1.2lbs. Barrel starts at just under 2" diameter towards the rear, tapers to just over 1" near the muzzle. The muzzle brake actually adds 5" in length, so the "combined" barrel length is actually 38" (as rendered).

This leaves a bit of room to reduce the weight, but I figure that the goal should be to reduce weight elsewhere in the design first, leaving the super-heavy barrel as an option that wouldn't put the total weight over 25lbs.

I don't think tooling would be too bad. Most of it was intended for milling machine and lathe construction, maybe some jigs and a mold or two for carbon fiber and plastic parts.

The .338 to .408 switch actually required a noticale increase in receiver size. Dropping it to .338 should easily let me drop the weight under 20lbs where it could be competitive with the AI rifles.

As to 6.8SPC, I believe that cartridge is an intermediate between .223 and .308, not really suitable for the long range shooting I designed this for.
If you meant the .416 Barret cartridge, I think that cartridge is a necked down .50BMG, and would require a larger receiver.

I'll need to see if I can get price quotes on the upper receiver from a couple shops. I think the aluminum alone would be around $500 or $600. I don't know what rates shops charge for milling machine time, or what the drilling would cost, but I imagine it isn't cheap. I also don't know what the legality would be, considering that the shop would be constructing a firearm receiver.
I think I'd need to work something out where I was at the shop, and hit the "start" button myself. That or do the 80% receiver route, finish it myself...

August 8, 2006, 11:46 PM
think about welding blocks onto an extrusion.

Don't make chips if you don't have to.

August 9, 2006, 11:07 AM
dfaugh, looking at that design, he'd be lucky to get the first 10 made for anything less than $200k. I don't think a $4000 version is too likely.

Oh, I don't doubt that building a few prototypes will be fairly expensive (although I think $200,000 is probably excessive)... But once you've worked out/made the proper tooling, costs would go down significantly.

Jim K
August 9, 2006, 03:19 PM
In any case, you would have to sell a whole lot of them to justify tooling costs. Maybe I am completely off the wall, but I just don't think the mass market is there for another bolt action super-sniper rifle that weighs 25+ pounds and has (IMHO) limited appeal. The writeup in G&A will be great, with lots of pictures of blown up plastic jugs, but that does not translate into firm orders, as many people with new gun ideas have found out.

Also remember that an old gun industry rule of thumb is that the retail price has to be around 7 times the production cost to allow everyone in the chain to make money. So if the gun costs $1000 to make, it would have to sell for $7000 at retail to make money. As to $200k development costs, that is small change for a real development effort. Developing a totally new rifle can take years, cost in the millions, and produce a lot of scrap metal.

(Now Boonie will produce his gun, which will sell by the thousands and make him a multi-millionaire, and I will have egg on my face. Could happen, I just don't think so.)


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