Big Bore AR-15

[Paul Groth]

So because Shop Monkey and myself cant leave shit alone and are always experimenting. Im now building myself a 16" 450 Bushmaster upper. Just curious if anyone else has experience with any other big bore AR-15 uppers. 450 Bushmaster, 458 Socom or 50 beowulf.

[steve_k]

I'm curious to see what feedback is provided. Recently I acquired an AR upper in 350 Legend from a deceased friend and have not really heard much about this caliber previously.

[LawDog]

So because Shop Monkey and myself cant leave shit alone and are always experimenting. Im now building myself a 16" 450 Bushmaster upper. Just curious if anyone else has experience with any other big bore AR-15 uppers. 450 Bushmaster, 458 Socom or 50 beowulf.

I have shot all of these. (Alaska is a weird place.) But I've only been through a mag or so of each, and they were far separated in time; I didn't get to shoot them side by side. My minimal experience left me with this impression:

It is a weird attempt to turn an AR-15 into a slug gun. It radically alters the recoil impulse in a bad way. It cuts the capacity of the gun down to something like a tube-fed gun. The role in which I saw them cast was that of a defensive bear gun. After shooting them, I would definitely have chosen to just stick to an 870 for that purpose.

I lack sufficient interest to devote my own time and money to the experiment, but I would be more interested in seeing the results of an AR-15 chambered in .338 or .358. The jump to .308 is easy and seamless. The jump to .458+ is--to my eye--a step too far. But I'm not sure where the dividing line really exists. How much ammo capacity is lost with a .358? Is the little case capable of propelling those bullets to enough speed to be effective?

I don't have a lot of information to add, but realizing that these are pretty rare I figured I'd share my $0.02.

[Dorkface]

A 458 socom is on my list to get. It can do everything from supers to heavy subs. The history is interesting as it was designed to have more knock down power than 5.56 and use off the shelf stuff. It uses a lot of the stuff 4570 does. If components or ammo ever become available for it...

[Knowledge]

I run the 458 all the time hunting. Two uppers one for day, one for night. Run the SC Hybrid on it and it's just perfect. 300gr ttsx is my favorite. Fast follow-up shots. I load some but I also stocked up from SBR. They'll bury me with my 458 when the time comes.

[DogDoc]

It'd be AR10 platform, but the fellow that invented 300 blackout has developed an 8.6 Creedmoor or 8.6 blackout (whatever they decide to call it)...basically what 338 Federal should have been. They do really fast twist barrels on them and it makes quite a thumper with supers or subs. I don't know that I can get excited enough about a new caliber to buy one, but it might be fun.

[Paul Groth]

Let me add a little bit to first statement. This all started cause i have been trying to find a reasonably priced Lever action 45/70, preferably a Henry but i am not picky, for about 3 years now to use as a bear gun hunting the thick brush of Arizona. I to this day still have not managed to find one. With comparable bullet weight of say 250grs the 45/70 is only about 100fps faster than the bushmaster. This rifle with a 16" barrel will fill that role of a brush gun well.

[LawDog]

Let me add a little bit to first statement. This all started cause i have been trying to find a reasonably priced Lever action 45/70, preferably a Henry but i am not picky, for about 3 years now to use as a bear gun hunting the thick brush of Arizona. I to this day still have not managed to find one. With comparable bullet weight of say 250grs the 45/70 is only about 100fps faster than the bushmaster. This rifle with a 16" barrel will fill that role of a brush gun well.

That helps. With that as background, I'd say you'll fulfill your objective. Personally, I'd rather have the 45/70 lever gun (and it sounds like you would, too), but this gun will perform the same task. Of the several people I know who have run such guns, none of them complained of reliability problems. (Though I'm confident that they didn't shoot them as much as their 5.56 guns, either.)

[Knowledge]

Let me add a little bit to first statement. This all started cause i have been trying to find a reasonably priced Lever action 45/70, preferably a Henry but i am not picky, for about 3 years now to use as a bear gun hunting the thick brush of Arizona. I to this day still have not managed to find one. With comparable bullet weight of say 250grs the 45/70 is only about 100fps faster than the bushmaster. This rifle with a 16" barrel will fill that role of a brush gun well.

Yeah that’s what drove me to the big bore ar. It’s the best brush gun I’ve ever used. Again don’t discount the fast follow up shots. I was in the middle of about 6 wild hogs once that were driven to me. I was able to put 3 of them down on my right and left at about 5 to 7 yards each in the thicket. That’s where the vortex 1.5x8 shined. I don’t have bears but hogs, axis and white tail have all fallen to it. I don’t think you can go wrong with a light fast big bore but all I know is the 458.

[JimD]

My buddy in OH has the 450 which he uses for hunting. I zerod it for him a couple years ago and he's killed quite a few deer since then, pretty much all fell on the spot. His ammo pushes. 200 gr bullet at 2500fps, which is essentially what a 308 would do. Ammo is expensive but he's only shooting 1 or 2 to check the zero and another 2 or to shoot deer. He loves it.