450 Bushmaster in AR15

Thebear_78

Handloader
Sep 30, 2004
3,047
669
I put together one of my Christmas presents today as the final parts came in. An AR15 upper in 450 bushmaster.

I know a few of you guys are using the 450. Anyone loading for it? What does and bullets are you running?

I can’t decide what I’m going to do for optics. Either this PST 1-4 or a red dot. Either way I’ll have backup irons.

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Sure is a big looking hole in the end of that barrel!

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That’s cool. Great thumper AR!

I have a .458 Socom I chambered from a very old Douglas blank. I put it on one of my flat back stagger feed Savage’s. Had a hard time getting it to feed, ended up MacGyver-ing a center feed .308 mag to make it work. Feeds well with Barnes Originals, will not feed reliably with flat points or RN. Some day I will locate a Mossberg MVP in .223 that uses AR mags and dedicate it to that.

I think the Bushmaster uses .452 pistol diameter bullets. Probably a better way to go. Had I had the right barrel, I’d have done a Bushmaster like yours or 45 Raptor instead.
 
I think the .452 bullets available are better suited to the 450s velocity potential. It’s basically a 460 SW, in an auto carbine. Any of those great 250-300gr pistol bullets should perform very well. Also hard to beat dirt cheap 45 hardball 230s for practice bullets.

I think I’m going to go with a red dot and sights on this thumper. The Sig redot has a 62k hour battery life, I can just leave it on all the time and replace batteries every couple years!

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I agree. The bullet line up is way better in .452. I think Barnes makes a dedicated SOCOM ttsx, that’s about it. I was hoping to get into casting, an itch I have yet to scratch, with this one. If I could make the darn thing feed anything other than spitzers I would be more inclined. Now it’s on the shelf.

There are some cool heavies out there for subsonic. I think it would be fun to suppress one. The 100 yard numbers with a 500 grain bullet are impressive. So many vices, not enough funding. Hahaha.
 
My buddy built two socoms for the fish & wildlife. One in an AR15, the other was on a Ruger 77 that started as a 22-250. They were both throated for the heavy hornady 500gr RN for subsonic/suppressed use for shooting problem moose/bears in town. They really worked like a charm.

I looked at a suppressor for this 450, bowers makes one that looks pretty good. Maybe down the road.


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Nice looking thumper! When I built my SOCOM, I went with a 2-10 scope and 45* offset flip up iron sights..The offset sights work well, but on the big thumpers it takes a little getting used to holding the rifle at a 45* angle..But I imagine if the need arises to put down a hog or bear up close, they'll do just dandy, and be there as backup should something happen to the scope. They fold neatly against the rail, out of the way when not in use.
 
I just recently went the 458 SOCOM route. Just slapped a new RRA upper on my AR-15. I shot it yesterady for the first time. I used Hornady 300 HP, Hornady 350 JFP and Barnes 300 TTSX bullets. All of the bullets fed and fired well. Interestingly enough, they all dropped into the same 2.5" orange dot at 100yds.

I was expecting a fair amount of recoil but was totally fooled by the mild recoil in the AR platform.
 
Got out to shoot the 450 BM tonight. It was a balmy -4 but otherwise a nice clear day.

The red dot cowitnessed the sights, was easy to get zeroed out at 25 yards, and the rifle functioned perfectly. The superlative arms adjustable gas block was really easy to adjust down to get the brass to drop right at 2:30-3 o’clock position.

The first three rounds at 100 yards
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1.5 MOA is about as good as I can do with a red dot at 100 yards. It almost makes me want to reconsider going with the red dot vs a magnified optic. One of the current 1-8 would be pretty sweet.

I think I will leave it this way for now though.
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I only had 20 rounds with me but was very impressed with them. I was easily able to whack my 9x12 gong at 100 yards both offhand and supported. It swings the gong pretty good!

Now I just need to get some dies and components. This thumper AR is a lot of fun.


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I was hoping to hear from salmonchaser. I remember hearing they used a 450 for bear defense at his lodge.


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My bad, I've been unable to log on for a while. Just got that resolved, for good I hope. Missed most of the action on Aprils shot gun selection too.
I've put together a couple of them now, had zero issues.
Ours are 16 inch, six position stocks. Optics are Leupold Delta Point, also BUIS equipped.
I use a CQB sling that keeps the rifle pinned to my chest, I can kneel down and release fish, rifle does not get in the way a simple tug makes it ready.
I never got to reloading for the rifle mainly because I didn't want to pack it back and forth.
My BIL was loading for us, had a couple failure to feed issues, went back to factory ammo, standard FTX.
Reportedly it's constructed heavy enough but Buffalo Bore came out with a 360 grain hard cast at 1800 FPS. That is our duty load.
At $3.00 a round I've only fired a few rounds to confirm function and zero. I did whack a couple of porcupines with it.
The rifle is easy to shoot, I've killed a couple of porcupines at 200 to 225 yards. Much past that it really starts to drop.
The Delta points have proven to be utterly reliable. Banged around, in and out of boats and airplanes, never cased, think of all the ways a fishing guide might abuse a rifle/optic.
The first one is getting ready for season 10. Still works great.
We have a lot of the factory FTX ammo, a number of the guests will shoot the rifle. Most are amazed how easy it is to use. I think you'll find it very suitable for the task at hand.


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The final version of my 450 bushmaster.

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I have two loads that I’m shooting. 250 FXT @ 2230fps and 275 TSX @ 1980fps. They both group to relatively same poi. The 275s hit about 2” higher at 100 yards. It’s currently zeroed an inch low at 100 with the 250s, and an inch high with the 275s. With the red dot they all seem to land in the same 3” group.

I’m planning on using the 275g load for bear defense and probably the 250s for black bear over bait.

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Great news, dang bears will be waking up before you know it. Great looking set up. I really need to add lights.


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