450 Bushmaster Upper

I bought one of the Bushmaster brand (in .450 Bushmaster) uppers on sale at MidwayUSA. I put a Japanese 3x9 scope on it for deer hunting (straight wall cartridge only) in my area. Shot 4 deer with it with 4 shots. All less than 100 yards. I did get a RRA magazine. It feeds better than the Bushmaster magazine in my particular rifle. You can't go wrong with a quality upper.

bear creek anything is garbage. Some shoot ok but that’s the minority. Contact Mos-tek and tell them what you want and they will set you up. The 16 twist barrels are great for subs and supers. The 20-24 twist barrels are good with supers. I have A mos-tek 10.5” 16 twist and it shoots great. It doesn’t get much use anymore after I put together a bolt gun 450.

Tromix has a couple configurations with 1:20 twists. I've never used his big bore stuff but I trust his reputation.
https://tromix.com/product-category/450-bushmaster/

steve101610 said:

bear creek anything is garbage. Some shoot ok but that’s the minority. Contact Mos-tek and tell them what you want and they will set you up. The 16 twist barrels are great for subs and supers. The 20-24 twist barrels are good with supers. I have A mos-tek 10.5” 16 twist and it shoots great. It doesn’t get much use anymore after I put together a bolt gun 450.

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Mos-Tek isn't very good either. I have a 12.5" Mos-Tek barrel on my 450 Bushmaster SBR, and it's basically a $700 paperweight.

Accuracy is fine, it's right around 1.25 MOA, and I feel like that fine for a short big-bore. However they did not deliver a barrel that was even close to what I specced. It's way over-gassed (I run it suppressed) because they did a pistol gas system instead of the carbine length gas system I specced. The gas block journal was oversized and I had to hone out the inside of the Superlative Arms gas block that they provided, which tells me they did not check fit and finish. And lastly they got the muzzle threads wrong too, and delivered it with 11/16X24 threads instead of the 3/4X24 threads I specced.

The cherry on top is that it took almost six months to get delivered. I should have rejected it and asked for my money back, but I just wanted to go shooting and I tried to make it work. Now I have a rifle that doesn't feed properly, ever, despite infinite tuning and trying every buffer combination under the sun.

All this is just to say, I would spend my money somewhere besides Mos-Tek.

Get the 1-16 twist from

MMH said:

Thinking about getting a 450 Bushmaster upper. Are the cheap uppers (such as bear creek) OK or should I spend more for something like a RRA. Also, All the uppers I see have a 1:24 twist. Does anyone make a 1:16? Want a upper w/ a free float handguard & capable of shooting at a minute. Specific recommendations & experiances would be helpful.

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Faxon makes a 1-16 twist... much better than 24 twist 450 Bushmaster.
The only reason I choose the Faxon barrel here in 450 Bushmaster, is the 16 twist.

It will stablize 500 grain bullets for more subsonic fun, jacketed or cast lead.

Resize .458 bullets to .452 in a Lee die easy to do, to add more bullet variety... heavy to light bullets to your 450 Bushmaster shooting experience.

westford86 said:

Mos-Tek isn't very good either. I have a 12.5" Mos-Tek barrel on my 450 Bushmaster SBR, and it's basically a $700 paperweight.

Accuracy is fine, it's right around 1.25 MOA, and I feel like that fine for a short big-bore. However they did not deliver a barrel that was even close to what I specced. It's way over-gassed (I run it suppressed) because they did a pistol gas system instead of the carbine length gas system I specced. The gas block journal was oversized and I had to hone out the inside of the Superlative Arms gas block that they provided, which tells me they did not check fit and finish. And lastly they got the muzzle threads wrong too, and delivered it with 11/16X24 threads instead of the 3/4X24 threads I specced.

The cherry on top is that it took almost six months to get delivered. I should have rejected it and asked for my money back, but I just wanted to go shooting and I tried to make it work. Now I have a rifle that doesn't feed properly, ever, despite infinite tuning and trying every buffer combination under the sun.

All this is just to say, I would spend my money somewhere besides Mos-Tek.

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Can’t believe you didn’t send it back or at least contact them. Mistakes happen to even the best companies out there. Their customer service is great and I’m sure they will make things right.

Mistakes do happen...but he's listed too many mistakes on one barrel.
As he made requests for the build to his particular specifications...and they missed what appears to be everyone.
Not good for a "custom" barrel maker.

I wouldn’t be looking at this for accuracy per-se…450 BM basically has the ballistics of a thrown rock. Mine’s purely a deep-brush pig killer, and I can’t imagine actually taking a shot on game much past 50 yards or so.

My vote would be to spend the extra money on a higher end upper…or better yet, roll your own.

Had my 10.5” 450BM barrel spun up off a Satern blank (I think it was a Satern barrel anyway, might have been a Tromix) by Trident Armory back in ‘19, but it doesn’t look like they do that kind of work anymore based on their website; looks like they mainly just do training and stuff now.

Built it up on a spare billet upper receiver I had, after I opened up the ejection port for that big ass case:



Dremel FTW! LoL



If you build your own, please just make sure you get a receiver with a large enough ejection port already machined in, so you don’t wind up with a hack job like I did to this poor receiver. I did leave the little detent tab at the top so I could leave a dust cover on there to hide my shame!



Looked OK after Cerakote at least…



…and even though it’s only a 10.5” barrel, I went with a 15” hand guard to tuck much of my huge ass Bowers 458 vers can under there too. Nothing like an 11” long can hanging off the end of a 10.5” barrel!



Edit: gas block not installed in that test fit.



I’ve punched a fair bit of paper and shot a couple pigs with it, and it’s a hoot to shoot! Makes big holes!