What's the better big bore AR cartridge?

[TTv2]

By big bore I mean anything .40 caliber and up and is not a pistol cartridge. The three I've seen that stand out as being good for hunting are the .450 Bushmaster, the .458 SOCOM, and .50 Beowulf.

I'm kind of privvy to the Bushmaster because it uses the same bullets as .45 Colt does, which I reload for, but the .458 SOCOM seems more capable given it shoots heavier bullets.

 

[Fine Figure of a Man]

450 Bushmaster
Legal for deer in my state and cheaper to load for.
https://www.thehighroad.org/index.php?threads/what-big-bore-ar-15.838515/#post-10870395

 

[LoonWulf]

By limitations of the platform, there isn't alot of difference between any of them. The .450 has access to the cheapest bullets, the .458 has a shoulder, and the .50 is a 50

If your running a suppressor the .458 might be easier to get performance out of at subsonic velocity, just because it has readily available very heavy bullets. I don't know too much bout that ran my .458 unsuppressed with 300 and 405 grain bullets

 

[js8588]

450 BM seems to have the most options. If not for the rebated rim, 50 Beowulf would be awesome.

 

[TTv2]

I really don't see the point of .50 in anything other than the original 50 of the Browning Machine Gun variety, I only included it because it's really the only other big bore AR cartridge other than the .450 and .458.

I just looked at thread linked to in post #2 and one of the posters there said he has made a 400 grain subsonic .450 BM load. That's pretty cool, but the .458 is able to shoot that same bullet 600 fps faster, quite significant difference in velocity.

 

[LoonWulf]

http://www.450bm.com
These guys have done some work on the BM.....

I drove 405s from my 16" 458 at about 1650 I think, I'd have to go check.

The Bushmaster should come close to that, if you can get or make .452 bullets of that weight. There are some heavy .452s available, 375ish etc.

If you want to shoot 400+ tho the .458 does have a better supply of readily available bullets....tho again some guys have had good luck resizing .458s

Personally I prefer the .458, it's just a damn cool looking round. I like the shoulder, and extra capacity (tho it's not really that useful). If you don't mind cost the .458s the way to go Imo.
The bushy has more bullet options on the low end, and costs less. Honestly it's probably the more "practical" round. If I do another big bore AR it will be a bushy.

But I'm going to build an bolt gun .458, no question there.

 

[TTv2]

I guess the nice thing is I can always just buy both a .450 and a .458 upper and have both, test them, and sell the one that didn't perform to my liking.

 

[Llama Bob]

If the objective is hunting, I would STRONGLY recommend the Hawk bullets for this type of application due to their good practical accuracy and incredible tolerance for low impact velocities.

Looking at the available bullets, the .458 diameter has 300gr, 350gr and 400gr Hawks all in thin jacket for low-medium velocity. The .452 only has the 350gr in the thin jacket. For me personally, that would be the deciding factor right there. I think .452 is going to have fewer bullets tailored to the intermediate rifle velocities overall - like basically none.

 

[LoonWulf]

If the objective is hunting, I would STRONGLY recommend the Hawk bullets for this type of application due to their good practical accuracy and incredible tolerance for low impact velocities.

Looking at the available bullets, the .458 diameter has 300gr, 350gr and 400gr Hawks all in thin jacket for low-medium velocity. The .452 only has the 350gr in the thin jacket. For me personally, that would be the deciding factor right there. I think .452 is going to have fewer bullets tailored to the intermediate rifle velocities overall - like basically none.

I would think any bullet for the .460S&W would work well in the Bushy?

 

[GunnyUSMC]

I had been given thought to building a big bore AR these last few months. After some reading, I plan to build a 458 Socom. One is that there’s a better range of bullets made to preform at it’s velocities, no need to modify magazines and tapered cases tend to feed better in simi autos.

 

[mcb]

450 Bushmaster has ~60.0gr of H2O capacity and an operating pressure of 38,500 psi
458 SOCOM has ~61.6gr of H2O capcity and an operating pressure of 35,000 psi

Not really enough difference to make much difference.

458 SOCOM has a better selection of 400 gr and heavier bullets if you are not into resizing bullets. That said I have resize some 405gr .458 bullets for a subsonic 450BM load I worked up that worked pretty well.

The myth that there are few .452 diameter bullets designed for 450 Bushmaster velocities may have been true in the past but that myth needs to die now. It is simply not true anymore. There is a larger and growing number of .452 diameter bullets designed for 450 Bushmaster velocities. Barnes, Remington, Hornady, Lehigh, etc all make 450 BM specific bullets. In addition any bullet that works well in 454 Casull or 460 S&W are prime candidates for 450 BM. There are many good bullets in the 200gr - 350gr range that work very well in 450 Bushmaster. Not to mention you can load cheap plinking ammo with your favorite 45 ACP FMJ bullet.

 

[LoonWulf]

If the objective is hunting, I would STRONGLY recommend the Hawk bullets for this type of application due to their good practical accuracy and incredible tolerance for low impact velocities

Friend of mine just recommend Hawk bullets to me for my lighter loads in my .375.
Which brings me to another round I've been considering trying, the .375 Socom, mostly just cause I have the Ruger.

 

[TIMC]

I went with the Beowulf. Shot a lot of pigs and deer with the wulf. Never tried to load subs with it but I never wanted to shoot subs out of mine anyway. I’m running 335 grain bullets out of my wulf, cool rifle!

 

[Llama Bob]

I would think any bullet for the .460S&W would work well in the Bushy?

That's presumably true, but I'm just looking at what's available from my first choice bullet manufacturer for this sort application, and they've got lots of .458 options and very few .452. So while there are undoubtedly .452 bullets, there seems to be a notable gap. If you know the bullets you want are available in .452, then there's no problem obviously.

 

[TTv2]

That's presumably true, but I'm just looking at what's available from my first choice bullet manufacturer for this sort application, and they've got lots of .458 options and very few .452. So while there are undoubtedly .452 bullets, there seems to be a notable gap. If you know the bullets you want are available in .452, then there's no problem obviously.

Is there anything that a 325 grain bullet won't do that a 405 grain will?

 

[jmorris]

I drove 405s from my 16" 458 at about 1650 I think, I'd have to go check.

That’s about as fast as I have driven them.

Is there anything that a 325 grain bullet won't do that a 405 grain will?

I use mine for hog hunting with heavy subs. The only way to gain energy once you set a speed limit is with mass.

So say we are pushing the projectile at 1050.

A 325 will have 796 ft/lb
A 405 will have 992 ft/lb
A 500 will have 1224 ft/lb

 

[Demi-human]

I find the speed limit with pistol bullets is in the terminal effect, not necessarily the accuracy or mid-flight destruction. A fourty five XTP will hold till it hits a water jug, but not after. Not even long enough to hit the second jug, but I ran the test only once.
I was satisfied with a fourty five caliber varmint rifle.

Everything changes when hunting larger or going quiet.

 

[someguy2800]

In any of them I would use hard cast for hunting anyway so I would get the 450 for the cheap plinking bullets, straight wall case, and slightly more available components. 458 bullets are expensive. Even for cast bullets 458 is usually way more expensive for some reason.

 

[CraigC]

For me, it's .450 all the way. There is virtually no reason to even fart around with 500gr bullets out of the .458. Any bullet designed for the .454 or .460S&W will work in the .450. A 325gr Barnes Buster, Swift A-frame or Grizzly Punch will take all the heavy game you would want to tackle with the cartridge, up to and including 2000lb bovines and it will do it with authority. Even the available 400gr bullets are unnecessary. A 250gr cast bullet at 1100fps will exit on any deer that walks so the idea of a 500gr subsonic .458 for deer and hogs is just absurd. I guess some folks think the heavier bullet hits harder but that's just wishful thinking. Foot pounds be damned, it makes no difference if the bullet exits.

 

[jmorris]

I guess some folks think the heavier bullet hits harder...

It’s not a matter of thinking, rather mathematics anyone can do the energy calculations.

 

[mcb]

It’s not a matter of thinking, rather mathematics anyone can do the energy calculations.

Light bullets will usually achieve higher muzzle energy than heavy bullets for a given case volume and max pressure. Light bullets allow for more room for more faster-burning propellant. Faster burning propellants also tend to be more energy dense increasing the effect of the more usable case volume the lighter bullet provides. I have gotten over 3000 ft-lbs with a 200gr bullet in 450BM. I have not got much over 2400 ft-lbs with a 300gr bullet.

 

[jmorris]

You missed the premise of the previous posts.

 

[mcb]

You missed the premise of the previous posts.

I think your right. I went back and re-read the post I was replying to and can't figure out why I typed that replay. Sorry about that.

 

[GunnyUSMC]

No turning back now, just ordered a 458 Socom barrel and BCG. Guess I know what I’m building next.

 

[Llama Bob]

Is there anything that a 325 grain bullet won't do that a 405 grain will?

There's some difference in the breadth and depth of wound that can be produced if both are tuned for their respective impact velocities.

If you want to do a .450, there's nothing wrong with it. Just wouldn't be my first choice. I'd avoid the .50 Beowulf like the plague though - even though Alexander Arms fired Bill Alexander, his stench won't dissipate quickly and you can bet if he was involved it's poorly designed.