Big Bore AR

[USAF_Vet]

As I'm working on my AR 5.56 pistol build, I'm looking forward toward future projects.

On my short list is a big bore AR rifle build, using the same spec lower receiver as a standard milspec 5.56 lower.

I've narrowed it down to two different calibers.

.450 Bushmaster
.50 Beowulf

This will probably be a deer hunting rifle for the most part (my area allows for straight walled cartridges, with a case length between 1.16" and 1.80").

I have zero experience with either cartridge, aside from what I've read online.

Each looks to be about 250 yards max, and even that might be pushing it, but considering the woods and brush in my hunting area, that's more than enough.

I'll probably be sticking with iron sights for this as well.

Also I'll probably go with a 20" barrel, and most likely be buying a complete barreled upper with BCG.

Obviously the .50 is offered in heavier grains, but I don't honestly see the need for such a heavy bullet in a deer harvester. If ever I get lucky enough to draw an elk or bear tag in Michigan, either caliber would be suitable, but also I'd not be faced with the caliber limitation in the areas I'd hunt either game.

So what says the THR rifle gurus?

 

[ILikeLead]

I considered the same and finally settled on an ar10 "thumper". Went with rra. It has killed deer since then.

 

[USAF_Vet]

Is that thumper the .450 Marlin cartridge? If so, case length is too long for my restricted area.

 

[AKMtnRunner]

Considered this one? Pretty interesting.
http://www.mgpcustoms.com/358_MGP.html

 

[Welding Rod]

I have owned 2 450 BMs and 2 458 Socoms, and currently own a MP10.

With that, my first choice would be the MP10.

If I HAD to choose a small block, I would take the either the 458 or 50. I have never even seen a Beowolf in person so I can't speak about it, but I know I am not interested in the 450 BM. If you are curious why you can search for it with my user name as I have posted about it already.

The 458 seems to be a pretty well thought out big bore cartridge for the AR15 chassis. However inspite of having owned two I didn't shoot them a lot so I can't speak to their durability. Mag feed lips may have to be tweaked a bit for function with various bullets.

 

[USAF_Vet]

Considered this one? Pretty interesting.
http://www.mgpcustoms.com/358_MGP.html

Neat, but the slight bottleneck puts it out of the running for a lower Michigan straight walled hunting cartridge. If the straight wall wasn't one of my requirements, it'd get a closer look. I cast and reload for 9mm, so this is going to stay on my radar, just not for a close brush hunting rifle.

The 458 seems to be a pretty well thought out big bore cartridge for the AR15 chassis.

I had put this high on my list at first, but bumped it down, then off the list due to the straight wall requirement for centerfire cartridges in my area.

 

[Edster12]

My vote is for the 458 SOCOM but it does you no good, not straight walled. I believe the 458 is the only true "Plug N Play" option. No mods needed for the lower, and utilizes standard magazines. Plenty of different types of bullets for it. 250gr to 500gr options.

 

[jmorris]

I went through the same thing a few years ago. Wound up with the 458 socom, better bullet selection for what I wanted to do.

 

[dmurdach]

I love my 50 Beo. I dont hunt with it(though I'm sure any of the loads would be adequate), just a range gun for now, but would love to use it on a Hog hunt some day. 250 yds I think is pushing the limits of the bullet design, I have only went out to 150 and it has held decent groups to there, but nothing spectacular. I load 350gr XTPs, but have also done a few of the Powr Belt 500gr.

 

[ApacheCoTodd]

Given the VET's parameters and restrictions:

As he's only asking about two very specific rounds with real - not imagined limitations on his choices...

I go with the .450 after taking into account issues like projectile selection, standard velocities and energy and my natural fear that some day there could well be a .4999999"+ dimensional ban.

 

[MCMXI]

I have a .450 BM and have zero regrets. I chose it over the .458 SOCOM because I don't buy into the "better bullet selection". There are plenty of excellent .45 cal bullets for the .450 BM and you can swage any .458 caliber bullet down to .452 caliber if so desired. The only possible drawback is the need for a different follower which you can make from a standard AR15 follower if necessary. Also, .450 BM magazines are readily available. It's a great cartridge and very accurate out to 200 yards. I have a Leupold Mark 4 3.5-10X scope that will replace the scope shown below. This rifle has proven to be 100% reliable thus far.

 

[pjeski]

My vote is for the 458 SOCOM but it does you no good, not straight walled. I believe the 458 is the only true "Plug N Play" option. No mods needed for the lower, and utilizes standard magazines. Plenty of different types of bullets for it. 250gr to 500gr options.

My Alexander Arms .50 beo upper runs great on any lower I have, including a full auto M16 conversion. Pmags work well, even better than the .50 beo mag that came with the upper. Truly plug and play and very reliable.

 

[jmorris]

I don't buy into the "better bullet selection"

Then you must shoot light bullets. 255 grains is considered "heavy" in .452 diameter.

A 405 grain is a "standard" weight in .458.

I wrote better selection for what I wanted to do. That being have subsonic bullets that had a lot of energy, that takes mass and I don't think I have ever seen a 500+ grain .452 bullet.

 

[MCMXI]

Then you must shoot light bullets. 255 grains is considered "heavy" in .452 diameter.

There are plenty of 300gr bullets that work well in the .450 BM. I'm also interested in subsonic performance and a 300gr bullet with a MV of 1,050 fps is all I will ever need. Like I said, it's easy to swage down ANY .458 cal bullet but not so easy to go the other way. Also, if I want to shoot .458 cal bullets I'll use my Marlin 1895 SBL. We all make our own choices and I'm happy with mine. You seem to be happy with yours. Life is good.

 

[dprice3844444]

here's some other calibers including the 450 marlin ar-10 upper mentioned above

 

[USAF_Vet]

here's some other calibers including the 450 marlin ar-10 upper mentioned above

Casing is too long for the hunting restriction. (post #3)

 

[TIMC]

I chose the Beowulf for my thumper AR; the rifle is great fun and gets a lot of attention at the range. I doe think you are being a little over indulgent on your expectation of it being a 250 yard rifle Wih Either caliber with open sights.

 

[Sheepdog1968]

Something I've pointed out to others before and worth consideration. You might be able to buy a 45-70 lever action for the cost of the upper. If you want a big bore upper for your are that is fine as well.

 

[crash32]

I have the 50 Beowulf with a ACOG on it...... no regrets. Such a cool and awesome rifle which I use for deer hunting as well.

 

[Onmilo]

I don't know if you consider them Big Bore, but I have been thinking long and hard about an AR10 type rifle in .338 Federal.

 

[rb288]

I have a Bushmaster 16" 450 BM that, in my case, is a hog killing machine.
Using the 250 gr. Hornady SST I don't think there is anything I want to shoot where I would feel I was "under gunned".

 

[AgCatJHS]

The .50 Beowulf is a great round. Mine works fine with standard .223 magazines as do most I know if. Out of a 16" barrel you can push a 335gr at around 1900, a 375 Gr Barnes at 1800 and a 445gr Cast at 1600.

I have shot the .450 some and wasn't very impressed with it. Especially with the early factory loads. There are some newer bullets that are tougher and heavier now that should make a better choice.

 

[Lloyd Smale]

I too am a beo fan. Its the one the others are measured by. Nice thing too is its not only cast friendly but renieer makes there plated bullets, which buy the way are excellent medium game bullets for a heck of a lot cheaper the standard jacketed bullets. Mine will shoot the reneier solid into a inch at a 100 yards and the hp just a bit worse at 1 1/8. Like was said though its not a 250 yards round. Smacks the crap out of things out to a 150 though.

 

[Loc n Load]

50 Beowulf

I have a 50 Beo and have been shooting it for several years....definitely a "bigger hammer".....have deer hunted with it and have shot several deer within 150 yds with broadside shots and they dropped where they stood. I have also shot several dozen hogs with it in Texas and it "hammered" them as well. I think it is a great round in the AR platform.