The Best 450 Bushmaster Uppers for your Big Bore AR-15

Last Updated on January 5, 2021.

Gas powered rifles are getting really good these days. A precision AR-15 is almost as precise as a bolt-action rifle of the same caliber.

But it’s not all about increases in precision. AR-15 construction has improved to the point where the AR-15 platform can also handle big bore rounds like the 450 Bushmaster.

If you shoot a specialized round like the 450 Bushmaster, you probably also want to use the best components. And that means you want the best 450 Bushmaster upper that you can get.

Of course, we all have budgets. So we dug up the best 450 Bushmaster uppers in various price ranges. So you can find the one that works best for you.

American Tactical Imports 450 Bushmaster Upper
  • Built around a mil-spec, 7075-T6 aluminum upper receiver.
  • Salt bath nitride bolt carrier makes your action smoother and your rifle more reliable overall.
  • Parkerized handguard looks cool and provides a remarkably stable platform for sights and forend accessories.

SPOILER—if you’re looking for the best blend of quality and affordability, get the American Tactical Imports 450 Bushmaster Upper. It’s affordably priced. And it’s a solid upper receiver.

If you’re looking for something more affordable, less complete, or even more specialized, check out the rest of this article. We’ve got all the best 450 Bushmaster uppers arranged so it’s easy for you to evaluate all of them.

Top 450 Bushmaster Uppers on the Market Today

The Best 450 Bushmaster Uppers Reviews: Uppers that Handle the Big Bullets

The overall best 450 Bushmaster upper is up first. The remaining best 450 Bushmaster uppers at various price points are presented (you guessed it) in order of price.

Lowest price point: first in this article.

Highest price point (but with more performance): near the end of this article.

Choose your reviews based on your budget.

1. American Tactical Imports 450 Bushmaster Upper - Overall Best 450 Bushmaster Upper

This 450 Bushmaster upper is remarkably well-priced. But it’s no slouch in terms of build quality and performance. The American Tactical Imports 450 Bushmaster Upper actually has quite a few really nice touches, which you might not expect from such an affordable upper receiver.

The receiver itself is a standard 7075-T6 aluminum upper receiver, with a slightly larger ejection port to fit the 450 Bushmaster round. It’s nothing special. But it’s certainly not some shoddy upper receiver.

But the real creature comforts show up in the bolt, barrel, and handguard.

First, the bolt is salt bath nitride coated to improve the dry lubricity and make your rifle’s action smoother.

The handguard is a parkerized KeyMod handguard. You might not like KeyMod. But it works just fine. And it’s more user-friendly than M-LOK.

The thing I like about this handguard is that it’s very similar to a Bravo Company Manufacturing handguard (my favorite handguard). The only difference is that it uses a slightly different barrel nut and attachment system.

The mounting system isn’t quite as secure as the BCM mounting system. But it’s still very secure. You won’t have any issues.

It’s not related to the performance. But the handguard also looks really nice because it’s got some contouring on the front end. And looking cool is half the battle.

The last nice thing is the barrel. It’s a 16 inch barrel that’s finished with black nitride. But the muzzle brake is pretty niceIt makes it a bit more comfortable to do some big bore blasting.

The only real complaint I can find about this upper receiver is that the charging handle is a simple, mil-spec charging handle. It’s 2021. Enhanced charging handles are pretty much standard.

But that’s a pretty small gripe. For the price, this 450 Bushmaster upper is hard to beat.


  • Built around a mil-spec, 7075-T6 aluminum upper receiver.
  • Salt bath nitride bolt carrier makes your action smoother and your rifle more reliable overall.
  • Parkerized handguard looks cool and provides a remarkably stable platform for sights and forend accessories.
  • Muzzle brake helps make that 450 Bushmaster more comfortable to shoot.


  • Basic mil-spec charging handle is a bit underwhelming.

2. Aero Precision AR-15 Stripped XL Upper Receiver - Stripped 450 Bushmaster Upper

Aero Precision is one of the premier AR-15 component manufacturers. They make great parts that are remarkably well priced. So the Aero Precision AR-15 Stripped XL Upper Receiver is easily the best option if you want a stripped upper receiver for a 450 Bushmaster build.

This upper receiver is forged from 7075-T6 aluminum, just like all their other receivers. However, the ejection port has been enlarged to accommodate 450 Bushmaster rounds.

Even though the ejection port is enlarged, a standard AR-15 ejection port still fits this upper receiver.

One of my favorite things about Aero Precision parts is that the finish is exceptional. According to Aero Precision, it’s standard hardcoat anodizing. However, the finish on Aero Precision parts is remarkably smooth and thick.

The finish is durable. It looks great. And I suspect that it helps reduce friction, as well.

There’s not much else to rave about with this Aero Precision upper receiver. It’s affordable and really well made. However, I would prefer an assembled upper receiver. But you might enjoy putting everything together.


  • Forged from 7075-T6 aluminum.
  • Enlarged ejection port accommodates 450 Bushmaster, but still fits a standard AR-15 ejection port cover.
  • Anodized finish is durable, smooth, and looks great.


  • Some assembly required.

Some people bag on Radical Firearms. But I think it’s mostly because they’re suspicious of the price point. However, I’ve been quite impressed with Radical Firearms equipment. So I have no problem recommending the Radical Firearms Complete Upper Assembly .450 Bushmaster.

First, the bolt carrier group is melonite coated. This is a better coating than a simple mil-spec phosphate coating. It improves the dry lubricity and smooths out the action. It also seems more durable than the classic mil-spec phosphate coating.

This upper receiver has a bunch of other features. However, there are a few standout features that I’ll cover with the available space.

The barrel has a single feed ramp. Many 450 Bushmaster upper receivers have standard M4 feed ramps. That works well enough.

But the 450 Bushmaster bullet is shaped very differently than the 5.56mm bullet. So the single feed ramp produces smoother, more reliable feeding.

Then, the barrel is capped with the Radical Firearms Panzer muzzle brakeIt’s a solid muzzle brake that does a good job of making your 450 Bushmaster rifle comfortable to shoot.

Lastly, the handguard is actually well designed. It has a bunch of M-LOK attachment points at the 9 o’clock3 o’clock, and 6 o’clock position.

However, the handguard also has picatinny rail sections near the muzzle end which are great for mounting lights, sights, and other forend attachments that often come with picatinny mounts.

The charging handle is a standard mil-spec charging handle, which I always count as a negative when there are so many enhanced and ambidextrous charging handles on the market.

But it’s a minor complaint. Even with a mil-spec charging handle, this Radical Firearms model is still the best 450 Bushmaster upper for the money.


  • Melonite coated bolt carrier group produces a smoother action and holds up better than a mil-spec phosphate finish.
  • Single feed ramp enhances reliability.
  • Panzer muzzle brake actually offers noticeable recoil reduction, despite the simple design.
  • M-LOK handguard has strategically placed picatinny rails that improve the accessory compatibility.


  • Mil-spec charging handle is disappointing, even on such an affordable upper receiver.

4. Bushmaster .450 Bushmaster Upper Assembly - Value 450 Bushmaster Upper

Bushmaster created the 450 Bushmaster. So it seems reasonable that the Bushmaster .450 Bushmaster Upper Assembly would be a decent upper receiver. And it is a decent upper receiver.

First, this upper receiver has a heavy barrel. The heavy barrel improves organic accuracy. And it resists heat buildup better than a standard profile barrel. This keeps your point of impact more consistent as you fire rounds and your barrel warms up.

The anodizing on all the parts—the receiver, barrel, handguard, etc.—is thick and smooth. It’s the sort of finish I would expect from a Bushmaster component.

However, the bolt carrier group appears to be phosphate coatedThe coating is consistent and applied well. It works well. But it’s still a phosphate coating.

The barrel is fitted with a muzzle brake that works better than a flash hider or compensator in terms of reducing recoil. However, it’s only okay as far as muzzle brakes go. You could definitely ease the recoil even more with another muzzle brake.

The handguard is another component that comes with ups and downs. The handguard itself is a free float handguard that’s machined from aluminum. It’s got a nice knurled section that’s comfortable.

However, it has no real forend attachment points, except for a sling swivel. So the handguard limits your potential attachments. But it’s a non-issue if you use a scope.

One last recommendation: I suggest that you give this upper receiver a solid inspection when you get it. There have been reports of receivers shipping with assembly issues. The parts are fine. But you just need to make sure that everything is put together properly.

However, instances of mis-assembled receivers are low.

The assembly issues are a little bit surprising, because Bushmaster is usually spot on. But that can be remedied with a little elbow grease. For the price, this is still an excellent 450 upper that offers solid precision.


  • Heavy barrel improves organic precision and resists heat build up.
  • Anodized and phosphate finishes are thick and well-applied.
  • Muzzle brake offers reasonable recoil reduction.
  • Comfortable, free-float handguard.


  • Handguard offers no attachment points beyond a sling swivel.
  • Receivers occasionally ship with assembly issues.
  • Standard mil-spec charging handle is merely adequate.

5. GLFA AR-15 Complete Upper .450 Bushmaster - 18 inch 450 Bushmaster Upper

The GLFA AR-15 Complete Upper .450 Bushmaster is a solid 18 inch Bushmaster upper. Most AR-15 upper receivers are built around 16 inch barrels because that’s the most common AR-15 barrel length.

However, this upper receiver has an 18 inch barrel. And it’s a chrome moly barrel. You may prefer a stainless steel barrel. But the barrel on this upper is meets the mil-spec standards. And it produces solid precision and muzzle velocity, thanks to those extra two inches.

The barrel is also finished in black nitride, which is actually a step up from a standard mil-spec finish. The bolt is also finished in black nitride, which reduces friction and produces a smoother action.

Unfortunately, the muzzle device is a compensator. It’s a good compensator. But a muzzle brake seems more appropriate for a 450 Bushmaster rifle. But a compensator is better than nothing.

The handguard is mostly a standard 15 inch M-LOK handguard. But it’s a slim handguard. The circumference is comfortable. The handguard is ideal if you prefer not to use a foregrip.

Lastly, there’s my usual gripe: the mil-spec charging handle. We’re in the golden age of charging handles, and companies are still using these.

But this GLFA accessory is still a great option if you’re looking for a 450 Bushmaster upper that has a slightly longer barrel for more muzzle velocity without making your rifle too unwieldy.


  • 18 inch barrel gives you solid muzzle velocity without making your AR hard to handle.
  • Barrel and bolt are finished in black nitride.
  • Compensator works well as a compensator.
  • M-LOK handguard is slim and comfortable if you don’t use a foregrip.


  • A muzzle brake would be a more fitting muzzle device.
  • Mil-spec charging handle is weak.

I’m from Nevada. So, naturally, I had to throw in a Franklin Armory upper. But the Franklin Armory Praefector 450 Bushmaster Complete Upper Receivers is a legitimate 450 Bushmaster upper.

The reason I call this a precision upper receiver is because it’s got a 20 inch barrel. That gives you the best muzzle velocity and precision from your AR-15. It’s great because it gives you the best long-range performance from the 450 Bushmaster.

However, the 20 inch barrel makes your AR pretty long. It kind of makes your rifle a dedicated long range rifle, because it could be a bit tough to lug around in the brush for hog hunting or something like that.

The barrel is a medium profile barrel, which is more precise and resists heat buildup better than a government or slim profile barrel. Though it’s not quite as solid as a heavy profile barrel.

The muzzle device is a flash hider, with some compensation slots. It’s a decent muzzle device. But I prefer a muzzle brake on a big bore rifle like a 450 Bushmaster AR. The muzzle device is better than nothing, though.

Additionally, this upper receiver comes with sights, which is more than almost any other upper receiver comes with. Might not be a huge deal if you’re planning on mounting an optic. But you still get sights.

Lastly, the forward assist is moved forward to make it easier to use, in the event that you have an issue that a forward assist helps with.

Yes, this upper receiver has a mil-spec charging handle. But that’s a small complaint. The upper receiver itself is excellent. Franklin Armory makes excellent firearms. And this is an excellent upper receiver.


  • 20 inch, medium profile barrel is excellent for long range precision.
  • Flash hider muzzle device works well enough and offers some compensation.
  • Includes flip up sights.
  • Ergonomically positioned forward assist.


  • A muzzle brake would be more appropriate for a 450 Bushmaster rifle.
  • Mil-spec charging handle is pretty underwhelming.

Bringing out the Big Bore

The 450 Bushmaster is a specialized round. So it makes sense that you’d get a specialized upper receiver to really dial in your 450 Bushmaster rifle.

You’re paying for the ammunition. So it stands to reason that you’d want to get the best 450 Bushmaster upper that your budget allows.

American Tactical Imports 450 Bushmaster Upper

If you want a solid 450 Bushmaster upper that fits most budgets, get the American Tactical Imports 450 Bushmaster Upper. It’s definitely a solid upper for the money.

Still hemming and hawing on which 450 Bushmaster upper is best for you? You know the options now. Time to pull the trigger.