458 Socom

[Fudmottin]

I know someone who does barrels for these. Unfortunately, my gun making budget for this year is over extended. But it might be a nice project for next year.

Who here has experience with it? How do you like it? Can you reach 500 meters?

I don't want the SBR hassle, so if I order a 458 Socom upper, it will have a 16 inch barrel. Does this hurt the load?

[Colohunter]

I was looking into these for awhile, but just built a 6.8. You would have a lot of drop out to 500 meters. I think the 16" would be fine, most people seem to like to shorter handier carbines in this cartridge. I think it is made more as a brush gun than a bench gun.

[Spook]

Yes you can get to 500,but the trajectory was more like artillery than a rifle. My guess is this cartridge was designed for close quarter combat rather than target of opportunity shooting.

[Fudmottin]

I'm not saying I would reach out to 500 all the time. That is mortar fire with any subsonic thanks to our friend gravity. Just the ability to do so would be nice though.

The reason for sticking with 16" is not just the SBR tax. Once a receiver is registered as an SBR, interstate transport becomes a big headache. I live very close to state lines and I do travel.

For the time being, silencers don't have that problem. Although I would have to rely on the GOPA because the surrounding states say nyet to them.

My 300-221 upper is a heck of a lot lighter than my 223 upper. I had the 223 done as a bench gun for long range shooting. The barrel of that weighs almost as much as the complete 300-221 upper.

I would expect a 458 Socom to be lighter still due to even more metal removed from the inside of the barrel.

[LouBoyd]

Just my opinions:
Long range subsonic shooting still requires low drag bullets. That's why the 300 Whisper is popular in the AR-15. It's about the heaviest low drag cartridge/bullet which can pass though an AR-15 magazine. The 338 Spectre can't handle the heaviest 338 bullets in an AR-15 magazine.
I own a 458 SOCOM RRA ar-15, and i don't consider it suitable for subsoinic shooting. It's fine as a short range hunting or urban entry rifle for bullets in the 90 to 350 grain range with standard supersonic loads.

The 458 SOCOM can be a great long range subsonic cartridge, but it needs at least a 30-06 length action and magazine. The Lehigh 582 grain 458 bullet is a good subsonic match for the case capacity of the 458 SOCOM That's the fifth cartridge in this picture:

[Fudmottin]

That puts a new spin on it. I guess one could go with a barrel on an Armalite AR-10 and get the action length of a 308. Still shorter than a 30-06 but close. That also makes it a much bigger project.

Could go with the DPMS LR308 too I guess.

Still, I think I'm probably going to pass. Leave that round for more serious people. If I was going to get that serious (hey, it's a new gun not just an upper), I guess I would skip over the SOCOM and go for one of the .510 wildcats if they don't go banning 50 caliber. I wonder how an AR-10 shooting a 50 caliber round would go over at the range.

[d-mon]

Hi,
What kind of barrel twist would be suitable to stabilize up to 500gr subsonic bullets of basic shape ie. flar base round nose?
I am just about to place an order for a barrel and want to make sure.

many thanks.
Nick

[Spook]

14 works for a typical jacketed 500 gr but the heavier /longer Lehighs require a 10

[LouBoyd]

I've bought an 8" twist Pac-Nor barrel to make a bolt action specifically for shooting the 582 grain Lehigh solid. The McGyro program says 10" might work but I wanted to be safe. 8" should be stable even transsonic at the elevation I shoot (mile+) It will be on a Rem 700 Long action using a 458X2 American cartridge (sixth in the row shown above). I haven't finished it so I can't tell you whether it will even shoot.

I chose the 458x2 over the 458 Socom because it has a much higher pressure rating. I'm of the opinion (but no solid proof) that fast burning high pressure minimum volume loads (within reason) for subsonics give low muzzle pressure and (most important) the smallest velocity dispersion. I'll find out if that's true with this beast. It will be a 16" barrel (to be legal). 10" would be a bit better ballistically. I'll experiment with lubrication to minimize bore friction. That may or may not prove to give better velocity uniformity but I expect it will.

Practical use? None. I'm only interested in learning about ballistics.

[HUNTER2]

Isn't the 458 x 2 real close to the 450 marlin? Benifits of each?