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Old April 19, 2012, 11:32 AM   #1
jason41987
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if you could design a rifle, what would it be?...

hey everyone... these last few weeks, ive been converting different sets of blueprints into 3D so that i can study the way each component reacts with eachother, how the different actions work and so forth... and at one point i felt pretty confident i could come up with my own design for a semi-automatic... sure, no harm in designing full auto in 3D.. however, im just not an advocate of it, i see it as a waste of ammo for the most part, so im focusing on semi auto only action...

so my question to everyone here is... what would you build if you could take any features, from any rifle and combine them into your idea of what the perfect rifle would be, or perhaps ideas of your own action?...

some options...

---

which action would you use?

gas operated, either long stroke piston (more reliable) or short stroke piston (less felt recoil usually)... also tilting bolt, or rotating bolt

recoil operated, long-action like a browning auto 5 shotgun, or short recoil action like that of a handgun, or the 1941 johnson rifle

blowback operated, either normal blowback like many low-caliber pistols and sub-guns, or delayed blowback like the G3/MP5 or french FAMAS?

blow forward, instead of the bolt being thrown back, the barrel is pulled forward by the bullet, off the empty cartridge and onto a new one

---

cartridge?

i dont think i have the months it would take me to list all of the options here.. so really, anythings possible

---

magazines?..

box magazines, would you make it accept a pre-existing magazine? if so, which ones?

rotary magazines, these seem to be rather reliable, simple magazines but tend to take up more volume than box magazines

helical magazine, which works like a spinning screw with the cartridges between the threads

enbloc, like the garand uses, which is like a clip that is fed into the internal magazine and ejects itself upon firing the last round

---

layout

would you go with a common layout with a magazine in front of the stock, which tend to be more reliable, with less muzzle raise when firing, a bullpup layout which is more compact and easier to maneuver, or something entirely different?

---

furniture

would you have a seperate forearm, stock, and grip, or would you go with a full one-piece stock?

----

anyway.. these are a few options that i can think of right now to point out some things available to anyone who might read this topic and not be entirely familiar with gunsmithing or engineering, but im confident most of you can ignore that part

so... my question is, what features would you choose if you could design your dream rifle, and why?
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Old April 19, 2012, 11:36 AM   #2
jason41987
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btw.. if anyone has any blueprints they would like someone to convert into a 3D format that can be viewed in 3D on a computer, and dimensions pulled from any piece, i could help, and distributors of 3D CAD/solid modeling software offer free viewers for these parts

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Old April 19, 2012, 11:50 AM   #3
RaySendero
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Jason,

I have always build or customized my rifles to/for a specific hunting purpose. Would need to you describe the purpose first.
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Old April 19, 2012, 12:44 PM   #4
jason41987
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for whatever purpose you want, and i dont mean assembling one from parts, but a design from scratch... this is a topic on theory more than anything else
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Old April 19, 2012, 06:23 PM   #5
darkroommike
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I very much like the CZ "short mauser" bolt action, except for the ugly magazine sticking out of the bottom. So there's a place to start.
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Old April 19, 2012, 07:41 PM   #6
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FNH PS90 that shoots .22 magnums

... must retain the same design and operating principles:

-ambidextrous
-bottom eject
-top - mount longitudinal magazine
-etc
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Old April 20, 2012, 07:56 AM   #7
jason41987
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anyone got an idea for anything more in depth than a conversion?
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Old April 20, 2012, 02:46 PM   #8
hhunter318
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Not a semi auto, but sort of on topic. I created an aluminum v-block on AutoCAD Mechanical and Inventor Fusion that accepted the Lawton 8000 action and AR15 style pistor grips. After I got that to spec I added a barrel shroud and some other accessories. In the end it looks like a clone of the Cheytac M200, but would be way cheaper to build when doing your own mill and lathe work.
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Old April 20, 2012, 05:41 PM   #9
animal
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Why bother designing a rifle after John Garand achieved perfection?
It even bites people you don’t want messing with it

Seriously, off the top of my head … gas op. long stroke, box mag., conventional layout, kevlar stock with inlaid T6 mounting blocks for receiver and bipod (made with the bipod integral to the stock so that stock is smooth when bipod is folded), receiver able to accept top mount scope, a sight (preferably peep) that could be used with scope attached .308 … deer hunting
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Old April 20, 2012, 11:05 PM   #10
jason41987
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i thought about using a round piece of tube steel for an upper receiver, so that i could use an extended portion, vented out and used as a handguard/shroud.... the way i set up the recoil spring stop was a plug in the end, pull, twist, release and the spring and carrier comes out...adding a lower receiver for the fire control group, and a wooden stock and it came out looking like a russian PPSH

i also have the idea of taking a .223 round, chopping it before the shoulder and use as rimless 357 magnum brass... necking it down (or leaving it straightwall) i would fit it with a pointed rifle bullet so out of the rifle, it would have more range/power than .223, while still being a pistol round (for logistics purposes of only having to buy one type of ammo)

some other ideas i had, just for the added simplicity was to go with a rolled delayed blowback system like the HK family of rifles because i wanted the recoil to be in-line with the barrel and stock, to reduce the overall felt recoil and muzzle flip... ive thought about ways to make a gas piston in-line with the barrel by using a cylinder shaped piston that would fit over, and ride on the barrel with a few smaller gas ports around the barrel rather than one bigger one...

those are just some of the ideas i had... you cant really design anything in this detail on a bolt action anymore, because anything you could have designed is already out there and in production, theres just no more territory left.. and i decide on semi automatic, because i just fail to see any practical use for fully even for military use (unless its belt fed).... so straight up semi for my design... never hurt the garand any
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Old April 20, 2012, 11:19 PM   #11
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hhunter318... i use autodesk inventor for all of my designs. i love it
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Old April 21, 2012, 12:56 AM   #12
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Dunno if I’m picturing your design correctly, but a one piece receiver/ barrel shroud sounds like a real mother to machine. Also, if the "shroud" serves as the gas tube for the center-bored cylindrical gas piston, it might create heat issues in the receiver as well as defeat the purpose of a shroud. Your gas piston also has far greater wear surfaces than a traditional piston. The bore of the gas piston alone would at least equal the the outer diameter of a traditional piston and that would be added to the much greater outer diameter of your piston . It might still work well, but tolerances might be a real headache.

On your cartridge : you might want to look up the "338-223 Straight", an obsolete (never was?) wildcat
Maximum for it was a 200gr spire point bullet at 1820 fps. And that would be HOT!, tho I have no idea what the actual c.u.p. was. This is about as big as you can get for a cut down .223 case. IMO, it would be under-powered for a deer and fall right into the category of "intermediate power"

The .357 bullet is larger diameter than the outer diameter of the .223 case at the shoulder (.354")
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Old April 21, 2012, 01:33 AM   #13
animal
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found a link for 338-223 Straight and mentions headspace issues

I think the ME for the 1820 fps load is wrong. Unless I've forgotten how to compute it over the years, it should read 1470 foot pounds for ME it looked funny, and I'm a bit anal (embarassed, but on the ther hand, being anal is one reason I'm still alive )

http://www.reloadbench.com/cartridges/w338223s.html

A discussion about rebarreling an AR in 338-223 and mentions .338 Spectre

http://www.ar15.com/archive/topic.ht...f=121&t=400962

.338 Spectre based on 10 mm case and headspaces on shoulder (funky lookin thing, but pretty neat cartridge for a variety of reasons)

http://www.teppojutsu.com/338.htm
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Old April 21, 2012, 01:41 AM   #14
jason41987
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see... the upper receiver would just be cut from a single piece of tube steel... the cylindrical receiver just extends in front of the barrel trunnion to form a handguard/shroud, like a sten crossed with a PPSH, the cost of manufacturing on a large scale would be fairly inexpensive...

but the problems raised with the piston ring over the barrel ive already noticed... delayed-roller blowback such as that on the G3 rifles, or CZ-52 pistol would be best, and maintain the simplicity of the design which, even though blowback does foul faster, would still be an incredibly reliable, simple design

another idea i had was to have a moving chamber that fits inside the trunnion... upon firing, the breach plug flies backwards from the energy, but never completely out of the trunnion, so no gasses get into the receiver, it hits a stop before that happens, and the momentum from this all, combined with a cam unlocks the bolt, and allows it to eject and chamber a new round... since ive never seen any firearm operate this way, its really hard to predict how it would work
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Old April 21, 2012, 02:25 AM   #15
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I don't know about the engineering aspect of it, but I'd like to see a semi automatic big bore carbine. I'm thinking M1 Carbine/Mini-14 size platform, doublestack stick mags. Chamber it in all of the big bore rounds from the 45 Win Mag up to and including the 50 GI, and the 50 AE. It must be button rifled so to be cast boolit friendly.

What a great hog gun this would make. Or brush gun. It would be a thumper and totally blow the heavy bullet ARs out of the water in usefulness. I want a 5 rnd mag for hunting and some 20 round mags. Iron sights, and not express sights, receiver mounted peep. 18.5" bbl., and don't forget the flash hider.
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Old April 21, 2012, 03:09 AM   #16
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hmm ok, I normally think of receivers as screwed solid as bloody hell to the barrel. What you’re talking about is pinning or welding the assy if cost and mass production is a factor ?
dunno if you could expect much inherent accuracy unless you go to a lot of trouble with an interference fit.

I don’t understand why you would want the chamber to move as that would increase bolt travel and it moving relative to the barrel would (I think) create nightmare gas issues. Maybe I’m missing something.

The only gun I can think of at the moment … that isn’t itty bitty and moves the chamber … is the Model 1911 Winchester shotgun. In it, the chamber is stationary with respect to the barrel … the entire barrel assy moves back upon firing and then rebounds forward … leaving the bolt at the rear and uncovering the empty shell as it moves forward for ejection and feeding the next one. … a simple recoil action, roughly the same bolt travel … and the barrel isn’t moving forward until gas is expended. The force of the gas pushing the barrel back delays the ejection.
You might say it’s a gas-dampened recoil-operation. The need for a delay in the action comes when you want to pull the empty from the chamber after the barrel pressures subside (that the 1911 provides with the movable barrel). The delay mechanism is the connection to the force exerted by the gas.

Sorry if I’m being thick here, but I can’t picture what you’re trying to do. Good luck with it.
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Old April 21, 2012, 05:53 AM   #17
jason41987
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ive been trying to think of smaller rifle cartidges based on handgun cartridges.. like 357 mag or 10mm necked down to take a 30 caliber bullet... a high enough pressure load with the right powder would come VERY close to .223 performance in a much shorter, lighter action, lighter rifle, and would be so much easier to carry large amounts of it on you, since it wuold just be a scaled down rifle cartridge
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Old April 21, 2012, 06:41 AM   #18
Jim Watson
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The Winchester Model 50/59 shotgun has a floating chamber, recoil operated. Seems a complicated setup to me.
As is the H&K roller locking system. Jeff Cooper said of the P9S, what money they saved with sheet metal and plastic construction, they plowed back into an elaborate barrel extension and bolt head. OK if you are tooled up for mass production, but I bet the prototyping was a bear.

For a rimless .357 magnum, look at the 9mm Winchester Magnum, the Wildey caliber they did not build guns for. It is a 9x29.

There was an outfit in Atlanta that built a nice bolt action with one-piece barrel and receiver. Savage built a bunch of them in small calibers. An auto would be tougher.
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Old April 21, 2012, 08:11 AM   #19
jason41987
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well jim watson.. i had absolutely no knowledge on the winchester 50/59, so i found a diagram for it... and it uses exactly what i mentioned.. though a bit over-engineered and too complicated, the moving breech was exactly what i had imagined, and the breech only goes back 1/10th of an inch, so the gases dont excape...

my idea though was to have a cam on the bolt unlock it from the breechplug section, similar to how a short-recoil operation works with a pistol

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Old April 21, 2012, 08:46 AM   #20
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I'm always thinking about designing or modifying a rifle.

An example, going back in time, back to Vietnam, I'd liked the M16a1, and think for jungle warfare the way we worked I'd take the M16a1 in the same weight and configuration, EXCEPT, a 1:7 twist barrel and the rear sights of the A2. My ideal of the perfect battle rifle for Light Infantry.

For long range (hunting or target) a Model 70 Winchester in 270 but a barrel with fast enough twist for the 165-175 grn bullet. With the BC of that pencil bullet it would shoot like a laser.

Another ideal, Re-Barreling an M1 and chambering it for the 270 Win. of course you'd have to have the adjustable gas system.

I have a lot of dumb ideals, I could go on forever.
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Old April 21, 2012, 09:05 AM   #21
jason41987
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its so hard for me to think of a garand in anything but a .30-06 though... i have a 3D CAD program on my computer i use for engineering different things... ive designed musical instruments, fishing reels, furniture, and various mechanical devices... ive converted a 1500s era wheellock rifle into 3D, fixing some of the miscalculated dimensions here and there to improve the fit and finish of it... and ive also converted blueprints for firearms before....

so, ive actually designed a couple rifles with this thing... my first design was a long-stroke gas system with a rotating bolt, in this design i made the extractor and ejector components level with the bolt carrier itself, so that the bolt could be removed, flipped upside down, and reinserted into the carrier, causing it to eject out of the left side rather than the right, making my design ambidextrous and left-hand friends, with a closable guard over the ejection port on either side and for low cost and simplicity, availability of parts i designed it to take the AR-15s semi-auto trigger group

for my next design id like to go with a delayed blowback system, and try to achieve 1000-1400ft/lbs of energy from the muzzle using a rimless, necked down .357 mag (made from .223 brass)

heres one thing to remember about kinetic energy, which translates into ballistics too... if you double the weight of a bullet, you double the kinetic energy, however, if you double the velocity, you quadruple the kinetic energy, so by necking down the rimless .357 i was hoping to gain back the energy lost by the case capacity lost from necking it down and using a short, 110 or so grain .308 bullet with enough energy and accuracy to take a deer 200-300 yards out, essentially allowing me to replace a .223 in a shorter, lighter package... but of course, i have no test bed for this i would feel safe firing it from, so i may take a barrel blank, ream it for this round, then have a simple screw on breech i can use to test the round without actually putting it into a functional rifle (yet)
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Old April 21, 2012, 11:44 AM   #22
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Jason41987,

Are you in/were you in Mechanical Engineering? And if so, where, if you don't mind me asking.
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Old April 21, 2012, 12:03 PM   #23
jason41987
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out of highschool i did go for mechanical engineering... but i had some serious medical problems that took me a long time to finally get past...that was 7-8 years ago, ive stayed close to engineering since though, reading test books, running experiments and projects of my own, why do you ask?
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Old April 21, 2012, 01:18 PM   #24
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I'm a mechanical engineering student from Mississippi State and I was just curious. I don't state it much though, being this young some people tend to question your real experience with firearms. I've been tinkering with guns since my parents would let me, so.. Ya know. But, my question was just out of curiosity.
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Old April 21, 2012, 01:24 PM   #25
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On your cartridge again … a .357 bullet will not fit in a .223 Rem case. The case would have to be expanded at the end rather than necked down. A..338 bullet gives you a more-or-less straight case that would have to headspace on the case mouth … bad juju that gets worse the more power you try to squeeze out of it (and oddly enough also bad juju in very low loadings with heavy bullets, but that’s another subject).

If you want a necked cartridge to solve the headspace problem, you need a bullet diameter smaller than .338, or a case with larger diameter than the .223
Also, when you start packing powder behind a heavy bullet, the pressure curve can skyrocket if you’re not careful. Selection of powder and and other factors can become critical.

If you want a .357, a starting point might be to look into the .357 Herrett. If I remember correctly, it’s in the power range you’re looking for. Anyway, if it is, note its case capacity (with the bullet seated) and then find a rimless case large enough to neck down, cut down, whatever… so that the case capacity of your rimless cartridge is at least as much as the Herrett. A little extra case capacity is usually better … safety for you ….
And a playground for handloaders

Your flip-over bolt sounds like a neat idea.
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