if you could design a rifle, what would it be?...

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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)
 
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?
 
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.
 
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:D

Your flip-over bolt sounds like a neat idea. :)
 
Cool hhunter ! I was a EE major at MS State years ago(early ‘80s). Had to quit to take care of my family so I never finished.

Best wishes for you completing your degree.:)
 
Thanks for that, Animal.

I'm in my junior year so I have about another year or maybe year and a half to go. After graduating I don't plan to stray far from the firearm and ammunition industry. It's an exciting adventure to say the least.

Well, I'm off to the State vs. Tennessee baseball game then the Maroon and White spring football game. Take it easy and shoot straight.

hhunter
 
animal, my idea for the .223 case was to chop it off behind the shoulder, neck it down to .308 with an overall cartridge length of about 40mm.. thats my idea for the cartridge, you can find more .308 bullets than anything else it seems, so having that variety should help fine-tune a suitable load for it... meanwhile that 40mm overall length is still short enough to be used in a handgun... to use it in a handgun though someone would have to stretch the 1911 design about 6mm, and i believe 36,000 PSI would be your limit... but im focusing on a rifle right now.. perhaps a converted .30 carbine to fire this
 
hunter, for my firearms experience, ive been around firearms since i was about 3... shot my first gun when i was so young, all i can remember from the experience was being thrown backwards (it was a 12 gauge).... but my love for firearms, and love for engineering go hand-in-hand pretty closely, and the interest in the various mechanical mechanisms inside them lead me to begin collecting them many years ago (im 27 now)...

when you see most machines they serve a specific purpose well, and there arent too many restraints on them, but when you look at firearms they have to be reliable, durable, accurate, all while fitting into a package thats comfortable to hold, and atleast survivable to shoot... its a tall order that leads me to great admiration for the early designers of the modern firearm world, like john browning for example
 
Nicely stated. I concur with everything as you put it in the previous post. I was just stating that I don't say much about being a college student when posting on the forum.. There aren't alot, but there are the Nay-Sayers that will jump up and call you out stating that you don't have the experience to give a good opinion. As far as those people go, I don't let them worry me.
 
Sorry, I was confused on the cartridge. Now it’s sounding like a reduced-powered 7.62 x 39. Why not just use it ?

Not sure that there would be enough neck with a 7.62 bullet in a .223 case. There is (or was) the 7mm TCU that might fit your idea.
 
another cartridge for a suitable conversion is the 10mm, neck that down to 30 cal and you might have something... shorter case, but wider base diameter... the 224 boz for example (10mm necked down to .223) has around 900ft/lbs of energy at the muzzle... with the right powder, and a longer barrel you could possibly see 1200ft/lbs plus
 
hmm, more powerful than a .308, and a decent amount shorter too, sounds like a nice little cartridge to get behind in a new rifle design... but its still an odd ball cartridge, and doesnt seem like it would be worth replacing a .308 with due to availability of the .308... but hey, if you could chop .30-06 cartridges and make it then your ammo is as available as 30-06

id like to find out what the absolute best performance you can get out of an M1 carbine sized rifle though
 
oh.. if anyone reloads for .308, im curious to know the overall projectile length for grain sizes under 140 grains if anyone can measure
 
I’m a 30-06/.308 nut. Dunno if any of the following is useful to you or not, but here goes. …

A .308 Winchester is basically a shortened 30-06.
In metric, They could be called 7.62x51mm and 7.62x63mm respectively.

Additionally, the .308 has the same outer dimensions and neck thickness as the 7.62x51mm NATO. Case thickness is different in the head and part of the wall, so the NATO version has less case capacity. Pressure ratings are also different: the NATO version having less pressure than the upper limits of those allowable in the commercial .308 Win. From the outside, they are the same and are (for the most part) interchangeable. Usually the difference is not a problem unless you’re reloading or wanting to use heavier bullets in military semi-autos(that weren’t designed to handle the higher pressures of some commercial loads).
Some commercial loadings in 30-06 more pressure (or the wrong pressure curve) than the military loadings of 30-06.

Basically, you can’t feed a Garand a diet of heavy bullets without tearing it up and the same goes for military semi autos "chambered in .308". There are similar differences between the .223 Remmington and its military sister, the 5.56x45mm NATO. What matters here is not only the peak pressure, but the pressure at the time the bullet reaches the gas ports.

The .30 TC is another step in decreasing the case size in the family of cartridges based upon the 30-06 case.
What’s happened over the years is that improvements in propellant technology have allowed the case to be smaller.

The .30 TCU is different, and based on the .223 family of cases. I had never heard of it or the .30 TC until this discussion.

To measure case capacities, I pour known volumes of sand (or powder) into the case. The "measure, mark, measure" method for deciding where to cut one.
 
the .30TC is less than 1/10th shorter than a .308 with the same base diameter, or so this article im reading says... is it worth the pain in the rear of finding rifles to fire this, finding ammo for it, for less than 1/10th of an inch shorter case?...nothing went into the .30TC that cant just as easily be used in a .308 and give the .308 even more power still simply by using a different powder
 
Well, yes and no.
Part of the reason for a "new case" is to prevent people from ruining their rifles. Theoretically, you could use a new powder to soup up the .308 beyond the 30-06. Prbably be fine in most bolt guns, but any of those loadings would tear the hell out of a M1-A and many other semi-autos out there … not just the heavy bullet loads.
 
Standard Military loading for .30 M-1 Carbine yielded 110gr bullet @1975 fps, ME= 955.. In an old notes, I found 100gr @ 2170 (using 2400 powder), ME would be 1050.

I seem to remember that the military had stability problems with bullets over 110gr when developing this round, but dunno for sure.

Since it headspaces on the case mouth, it might cause problems if you tried to soup it up, especially in a semi-auto.

Never liked this round or gun personally. It seemed like one that was kinda between uses… What it was powerful enough for, it wasn’t accurate enough … and vice-versa. … Works good on feral dogs /coyote sized stuff, but I never trusted it beyond 100 - 150 yds.
 
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hmm.. 10mm has a significantly larger case capacity than 30 carbine and shorter overall length, and as much power from a pistol as the carbine produces out of the barrel... with the right powder that 10mm would absolutely dominate a .30 carbine
 
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