What big bore AR-15 ??

I was looking into this last night myself. If I were to go with a big bore AR, it would probably be a .450 Bushmaster. Ammo seems to be cheaper than .458 SOCOM or .50 Beowulf.

.452, .500 or .458? .452 is going to use cheaper pistol bullets. .458 has the best selection of “heavy” bullets. The .500 will let you tell people you have a “fifty cal” even if some will giggle when they find out it’s not a BMG after you were trying to brag about it.

The 450 Bushmaster uses the .452 pistol bullets the 458 socom uses the .458 rifle bullets.

I went with 450 Bushmaster. I have been having a lot of fun with it. I have yet to put a factory round through mine. Got a bunch of brass from a friend and have been playing with a bunch of different bullets. Everything from 200gr to 405gr so far. I hunted deer with it last year using Barnes TSX 275gr bullet but unfortunately got skunked so no terminal results to report yet. Hopefully this coming season will be better.





Ballistically speaking there is little difference between 450 Bushmaster and 458 SOCOM. 450 BM has a slight pressure advantage (38,500 PSI vs 35,000 PSI) and 458 SOCOM has a slight case volume advantage (61.6 gr H2O vs 60 gr H2O). Both are fun. What state are you hunting in? Some states, like Ohio, 450 BM is legal but 458 SOCOM is not due to their hunting regulations.

It's commonly repeated that 458 SOCOM has a better bullet selection but I don't see it anymore. With the rise of both 450 Bushmaster and the 45 Magnum pistol cartridge (454 Casull and 460 S&W) there a large and growing selection of good quality bullets that can handle 450 BM velocities. In addition I can load cheap 230gr FMJ 45 ACP bullet for plinking ammo. And if you want to go super heavy a pair of Lee sizing dies and you can resize most .458 diameter bullets down to .452 with a good close arch reloading press. Do it in two steps .454 then .451 and most jacket bullets will bounce back to .4515-.452. I loaded some Remington 405gr 45-70 bullets making a nice sub-sonic 450 BM load with them

Rambling

I went .458, mostly because I like the shoulder, and it looks cooler.
Functionally you may want to consider what weight bullets you WANT to shoot and go from there. Personally I would probably do the bushmaster if i do another big bore ar upper, just because mostly id want 250-300grn bullets.

If you want a big bore AR to spend time plinking, the .450B can utilize cheaper pistol bullets.

If you want a big bore AR to do work in hunting fields, the .458soc has the performance edge.

Varminterror said:

If you want a big bore AR to spend time plinking, the .450B can utilize cheaper pistol bullets.

If you want a big bore AR to do work in hunting fields, the .458soc has the performance edge.

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Expound on how 458 SOCOM has an edge hunting please.

mcb said:

Some states, like Ohio, 450 BM is legal but 458 SOCOM is not due to their hunting regulations.

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If you’re hunting Ohio, this answers your question

The 375 SOCOM looks fantastic on paper (basically .30-06 ballistics in an AR package) but does not have proper bullets. .375 H&H are far too hard and the .375 Win bullets bend on the semi-auto ride opening up groups and grenade on game.

Mike

I'm gathering parts to build a 450 BM. Legal for deer in my state and more economical than the .458

I'm going 458 socom mostly because I like a shoulder to headspace off of in a semi auto. And because there is a plethora of 458 bullets out there that work for it. Also true for the 450 bushmaster, LOTS of cheap bullets for it, but I just can't get comfortable with the headspace on the case mouth idea in an auto rifle.

I think I would go Bushmaster as ammo seems to be more available and with Ruger loading bolt guns for it, it is gaining popularity. However, I see any of them as a reloading proposition so that isn't a big gain. I've stayed on the fence for years waiting to see who wins in the AR "thumper" category.

adcoch1 said:

but I just can't get comfortable with the headspace on the case mouth idea in an auto rifle.

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Works just like a Nineteen Eleven.

I like the high velocity pistol bullets. It's like I have a fourty five caliber varmint rifle.

A while back I decided to buy one of the Ruger American bolt actions in each of the calibers I had an AR chambered in. I have the American Predator in 223, 308, and 6.5 Grendel. The Ranch in 5.56, 300 blk, and 450 Bushmaster.

The Bushmaster i did backwards, bought the Ruger, then built the AR. If Ruger made the American in 450 SOCOM i would have gone that route, if for no other reason than i like my cases to have a shoulder, but the 450 Bushmaster is no slouch. In the short time i have owned the rifles, they have accounted for 4 deer and a handful of pigs. Performance could not have been better.

.358 Win would be my vote

I like 450 SOCOM more than 458 Bushmaster....


Jk, I'd still pick 450 Bushy....