Building a hunting AR 15

[jmort]

"I'm leaning towards the 450BM for a couple of reasons most the same as the ones I lean towards 5.56 derivatives in AR's. You can use the same magazines so no need to buy all new ones. Factory brass from Starline (tons of 5.56 out there dirt cheap for conversion to whatever you want like 300BO)."

Please correct me if I am wrong, but it is the 458 SOCOM that uses standard mags without changing anything and the 450 BM that requires its own specialized single stack follower. Starline has them both covered. I like the SOCOM if I am going big.

[jonp]

Your right, a slight mod to the magazine for the 450 but the mag body can be used, standard for the 458.

[Swamp Fox]

jonp- The 450 bushmaster is where I’m leaning too. It’s got good power, good availability, and it looks like it’s going to be the most common of the big bore ar cartridges. If it gets more popular, hopefully barrel prices will come down, which seems to be the hold up to cheap builds.

My reason for not really liking the 300 BO are mostly just arbitrary personal preference. I think it’s a good round, and I know a couple people who hunt with one with good results. But I’m just not impressed by the ballistics. It’s a step down from a 30-30 (which I love and hunt with), and power falls off pretty quick. I normally hunt hogs with a 45/70, and love the knock down power. It’s probably my single favorite rifle, so I guess that’s what I compare stuff too when I’m looking at other guns to hog hunt with. It’s got a lot to do with why I’m not real interested in the sub 30 caliber stuff, even though I know they are good, capable rounds.
It’s kind of funny, the last 20 years we have been hearing how we need magnum everything to hunt anything bigger than squirrel. All the gun writers and keyboard experts put down the 3030 as being barely enough, but all at once the new hero cartridge comes out and it’s got plenty of power. When was the last time one of them recommended shooting a deer at 200 yards with a 30-30?

[moorvogi]

I also went down this path! Over the last year, i built a 300blk and a 458 socom. Built loads for both and got to say.. i like the 458 more. HOWEVER consider the SAMMI info posted above. Assuming you're looking only ar15 not ar10.. my money is on 458 over 300blk.. can't speak to the others.

If ar10, 308 can't go wrong.

[Petander]

Hornady 350 FN @ 1900 fps, 75 meters, Tromix upper. Sorry for the j-bullet pic but my cast loads are not this accurate,not yet.

This is normal accuracy for this bullet,no lucky group.

Attachment 232731

Attachment 232732

[jonp]

Hornady 350 FN @ 1900 fps, 75 meters, Tromix upper. Sorry for the j-bullet pic but my cast loads are not this accurate,not yet.

This is normal accuracy for this bullet,no lucky group.

Attachment 232731

Attachment 232732

Nice group. You talked me into it. What bullet is that?

[244]

By the looks of it, I'd say that is a 405 grain Remington bullet.

I have and love my .458 SOCOM. I worked up a bunch of loads for my 16" barrel (sorry, all j-word bullets) a few years ago. After the initial brass and die purchase, reloads are cheap enough. Just remember to use Large Pistol MAGNUM primers (unless Starline has changed their brass to accomodate LRP's lately).

If you are recoil sensitive, the 6.8 would be a good choice too, followed by the .300 BO, then 6.5 Grendel/.264 LBC. You can use faster powders in the 6.8 and .300 BO to get the most out of 16" or less barrels, but as mentioned before, the 6.5 needs the barrel length to work its magic.

[Charlie U.]

I went with the 20" factory upper in 450BM and paired it up with my 24" Bushmaster varminter. Makes for an excellent deer rifle in the fall and then switches back to my varmint gun when the season is over. I have a Timney Targa 2 stage trigger in that lower so this combo is excellent for precise shots in either configuration.




The 450BM is great for hunting hogs and deer. The 16" might be more to your liking, but I ran with the 20" purely out of personal preference. Both uppers wear Vortex scopes and I swapped out the factory flash hider for a Ross muzzle brake on the 450BM upper. Other than that one change they are straight factory uppers.

If I were to get one today it would be the Ruger MPR in 450BM. You can hardly build a better hunting AR for the price.

[popper]

458 Ham'r.

[Bigslug]

AR-15 - - WHY???

Based on your OP, a .45-70 Marlin would be a lot more straightforward and perfect for the job, with no need to wade through all the muck of figuring out what combinations of parts you need to make an autoloader run with a cartridge not even close to what it was designed for.

Buy Marlin, hang 1.5-5x scope, kill deer. Done.

[the_ursus]

Just started shooting a tromix 16” .458 and love it so far. This will be a hunting, target, bear defense etc rifle. I’ve primarily been working on cast rcbs 300 gr .458 flat point (335gr lubed and checked). It’s shooting about an inch at 50 yds with room for improvement I think. 39 gr R7 is as far as I’ve taken it and recoil at the bench is not overwhelming. Not sure of my cost per round but it’s very affordable with cast bullets so far. These big slow moving bullets are not likely to expand on game so I’m not expecting enormous wounds and penetration shouldn’t be a problem.

[Swamp Fox]

WHY NOT? Why do people climb mountains? Why go hunting at all? Wouldn’t it be easier to just go to the grocery store? I know it would be cheaper.
It you had bothered to read you’d know I have and love a 45/70 already. If not for curiosity and wondering “can I do this”, shooting and reloading wouldn’t be much of a hobby.

the ursus- what made you pick the 458 over 450 BM? Was it bullet weight/ availability?

[KCcactus]

I hunt with an AR in 6.8. 115gr Federal Fusion is impressive on both deer and feral hogs. The last Fusion I bought was on sale for $17/box with free shipping plus a $5/box rebate.

Recently picked up a Bear Creek 450 BM upper to play with. Managed to catch it in stock on sale at $208. They currently have 458 socom uppers for $240-250. I chose the 450 because my 45 cal molds are .452, I'm not interested in more than 300 gr boolits and factory ammo is less expensive. 250 gr at 2,000-2,200 fps is overkill for anything I'll find at my hunting spot, but it should be fun.

[Swamp Fox]

Those are pretty much my same reasons for leaning towards a 450 over 458. If I want to shoot a really heavy bullet real hard I can always get the 45/70 out. I’m still not fully decided, but if I had to order a barrel today that’s what I’d get. But I really love the idea of the 375 socom.
How about a review on the bear creek upper once you get it going? I’ve seen there stuff and wasn’t sure how good it would be. But you can get a whole upper for the price of a barrel anywhere else.

[BD]

I went through this decision process 10 years ago. I wound up building a 450B and never looked back. it's the 45 acp of ARs, lots of powders work, lots of bullets/boolits work, pressures are reasonable and brass lasts forever. Using the 250 grain FTX it can shoot exactly to the BDC reticules of both the Leupold and Nikon black powder scopes. Good for anything from 300 yards and under. I put it together and took it to the local, (at the time), range in NY with load work ups using the 250 grain FTX and 250 grain XTPs, Lil Gun and WC 297. I was shooting over the crony at 85 yards, (length of the range there), recording velocities. At the end of the morning I went down range and took down the target. All 80 rounds went into 1-1/4". I was sold. I'm about 2,000 rounds into it at this point, (mostly cast) and still smiling. I have a FTX target over my loading bench with a 1-1/2" group at 300 yards shot from a clean cold barrel my first day at the local range in SC off a rest. No sighters, just top of the post of the BDC reticule on the Leupold. About an inch to the right of the bull, but I'm not complaining. The only downside is that for best performance you really need to make a "neck crimp" die as the force of the bolt slamming home can override the Hornady taper crimp with heavy bullets, and if you use a roll crimp they don't always chamber consistently. The forum below is full of information. I was pretty active there when I was getting into this, not so much anymore. I use cut down .284 brass for bullets, (large primers, thicker neck, .452 bullets), and Hornady factory brass for bolts, (small primers, thinner case necks and small rifle primers). Lil Gun works great, but really heats up the barrel. H100 works, 296 works and I'm using WC 297, (just because I had 12 lbs on hand), and it works great too.

http://450bushmaster.net

[BD]

Another note: .450 B uses standard .223 AR mags with a "special" blue plastic follower, (my followers cost $3.95 back in 2009), or the Sig plastic 20 round mags right off the shelf, no mods needed. 20 round .223 mags hold 9 reliably. Biggest hassle is that if you're hunting with it you really should buy at least one 5 round Bushmaster mag that has ".450 B five round mag" printed right on the side or the local fish and game guy may try and take your mag apart to see if it's really limited to five rounds, (at least in Maine where I currently live).

[kbstenberg]

I am just starting to look into building a bigger better mousetrap. With both the 450 & 458 being shot out of an AR15. What has to be done to the BCG to handle the larger base?

[BD]

At least for the .450B, the bolt face is different, the rest of the carrier is the same.

[jmort]

After giving this more thought, and this thread was most useful, I am going with .458 SOCOM
Completely compatable with AR15

[Gtek]

For those diving into the SOCOM, please watch and inspect all when venturing into new loads. I will call it limited into this round and it went from nothing visible to trying to push the primer through the firing pin hole with just over a grain. This was especially evident when going with the heavies, start low, go slow and inspect each case until you have established, SOP you know the drill. There is growing load info online and I have enjoyed the ride so far. Another thing on the big holes, nobody dresses the extractor out. I am a LITTLE OCD and the extractors are always knives on outboard corners and eats ones brass really bad. Spend a little time and dress and roll corners, your brass will Thank You.