M1A carbine in .460 SW Magnum?


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desidog
May 12, 2009, 05:56 PM
I've been intrigued by the idea of a semi auto carbine in .460S&W; so i got to thinking, what about using an M1A/M14-type receiver and getting a .460 barrel? I imagine it to look similar to a SOCOM or Scout in appearance. The Smith and Wesson pistols have progressive twists in their barrels - so it would really be a custom job at the end of the day....driving the price up. But i'm thinking, if its a viable idea, why not make a "production run" of 25 or 50 of them to bring the cost down.

The barrel/receiver marriage and receiver strength are my top question, but i'd like to hear what others with experience with both, or either of the two main elements here think? Plausible alternatives?

Thanks, desidog

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t george
May 12, 2009, 06:08 PM
i donno but it sounds like a neat idea. if it works is sounds like it would be alot of fun but it would be for reloaders as 460 is pretty hard on the wallet

rcmodel
May 12, 2009, 06:10 PM
M-14 magazines & feeding might be a problem with a rimmed revolver round like a .460 S&W.

I doubt the progressive twist would be any more necessary in a rifle length barrel then it would be in a .458 Win or .460 Weatherby.

They both will push similiar .45 cal bullet weights 1,000 FPS faster out of normal rifling.

rc

desidog
May 12, 2009, 06:14 PM
The bolt-face is close, but not a match; here are the specs for a .308Win and a .460SW

.308 Winchester Specifications
Parent case .300 Savage
Case type Rimless, Bottleneck
Bullet diameter 0.308 in (7.8 mm)
Neck diameter 0.343 in (8.7 mm)
Shoulder diameter 0.454 in (11.5 mm)
Base diameter 0.470 in (11.9 mm)
Rim diameter 0.473 in (12.0 mm)
Rim thickness 0.050 in (1.3 mm)
Case length 2.015 in (51.2 mm)
Overall length 2.800 in (71.1 mm)
Rifling twist 1 in 12 in (305 mm)
Primer type Large Rifle
Maximum pressure 62,000 psi (430 MPa)

.460 S&W Magnum Specifications
Parent case .454 Casull
Case type Rimmed, straight
Bullet diameter 0.452 in (11.5 mm)
Neck diameter 0.478 in (12.1 mm)
Base diameter 0.478 in (12.1 mm)
Rim diameter 0.52 in (13.2 mm)
Rim thickness 0.059 in (1.5 mm)
Case length 1.80 in (46 mm)
Overall length 2.290 in (58.2 mm)
Primer type Large pistol

these specs are copied and pasted from wikipedia
http://en.wikipedia.org/wiki/.308_Winchester
http://en.wikipedia.org/wiki/.460_S&W_Magnum

case length is no problem, but is .52 vs. .473 a deal breaker? close enough to modify?

rcmodel
May 12, 2009, 06:45 PM
.308 Winchester Specifications
Parent case .300 Savage
Wrong.
The .300 Savage is a shorter case then the .308 so you can't make one out of it.
It was developed from the longer 30-06 Springfield cartridge then in service by making it shorter.

The M-14 bolt face & extractor would have to be modified to accept a larger rimmed case.

But again, you will have feed problems with a rimmed revolver cartridge in a staggered box magazine designed for rimless rounds.

They won't stack right.

There is also the possibility of the top rounds rim getting stuck behind the round below it's rim.
Thats called Rim-Lock, and will stop the gun in it's tracks until cleared.

rc

XTerminator
May 12, 2009, 08:26 PM
I think the 450 Bushmaster cartridge would work in an M1A with some modifications, or you you could just buy the 450 Bushmaster AR and not have to due any converting.
I've had one for about 6 months, one of my favorite rifles. :D

Steve

ColeK
May 12, 2009, 08:35 PM
Why would you want to do such a thing?

FiveBillionAcres
May 13, 2009, 02:38 AM
I don't see a clear advantage to this idea… Why spend all that time and money developing (or presumably having someone else develop) a gas operated semi-auto to fire ~300 grain bullets such that they would generate 3,800J of energy. It's been done.

If you want a soup can throwing semi-auto you could get an AR in .50 Beowulf or .458 SOCOM for a small fraction of the cost and avoid all the rimmed cartridge problems. I think the ammo might even be cheaper too, but I'm too lazy to check.

Now a leaver action that chambers (and shoot's acceptably well) .45 Colt, .454 Casull and .460 S&W Magnum, that'd be great.

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