.450 Bushmaster Ammo

Best .450 Bushmaster Uppers

Are you looking to either put together your own AR-15 in .450 Bushmaster or upgrade your existing AR-15 to the round?

Either way, you’ve come to the right place. No .450 Bushmaster rifle is truly complete without the upper receiver, because without it, your rifle wouldn’t even be able to function!

Needless to say, your .450 rifle is only going to be as good as your upper receiver is, and that’s why you will need to invest in the highest quality upper that you possibly can.

Best Stripped Upper Receiver Pick: Aero Precision Stripped XL .450 Bushmaster Upper Receiver
Aero Precision Stripped XL .450 Bushmaster Upper Receiver
The Aero Precision Stripped XL .450 Bushmaster Upper Receiver is ready to go for full customization as this is a true stripped down receiver. Look for a complete receiver though if you’re not willing to buy the rest of the components separately and assemble it yourself.

See on Brownells

Best Value Pick: Aero Precision Assembled XL .450 Bushmaster Upper Receiver
Aero Precision Assembled XL .450 Bushmaster Upper Receiver
The Aero Precision Assembled XDL Upper Receiver is a solid value for an upper receiver overall. You’ll need to buy and add things such as a barrel or a dust cover and forward assist, but it’s built out of solid materials and has a hard anodized finish for superior corrosion resistance.

See on Brownells

Best Complete Upper Receiver Pick: Radical Firearms Complete .450 Bushmaster Upper Receiver
Radical Firearms Complete .450 Bushmaster Upper Receiver
The Radical Firearms Complete .450 Bushmaster Upper Receiver, available in both twenty inch and sixteen inch barreled versions, comes with everything that you will need in an upper receiver including a dust cover and forward assist, features that are often not included on upper receivers.

See on Brownells

In this article we’re going to dive into what makes the .450 Bushmaster such a great round, the top components and features that your upper receiver needs to have, and then the top three best .450 Bushmaster upper receivers that are currently available on the marketplace.

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Why Go With The .450 Bushmaster?

The .450 Bushmaster was born from a concept of firearms legend Jeff Cooper. Cooper was not satisfied with the power of the .223 Remington or 5.56x45mm NATO cartridges when it came to big game hunting, but he was a fan of the AR-15 design itself. Cooper’s idea was to develop a bigger round that would be a larger bore caliber of at least .44 caliber but that could still be used and fired out of the AR-15 platform and using AR-15 magazines. As Cooper himself said, he wanted a “Thumper” round to be fired out of the AR-15.

LeMag Firearms listened to Cooper and developed what was called the .45 Professional round. After taking the round to the ammunition manufacturer Hornady, who requested that the round be shortened, the new .450 Bushmaster round was officially born.

The .450 Bushmaster was really designed with one purpose in mind: hunting. Similar to the .45-70 Government round, the .450 Bushmaster is designed to take down big game animals in North America from a distance of within two hundred and fifty yards. The .450 can be used on anything from deer to pronghorn to elk to bear, but again, it’s not intended to be a long range round. It’s a good round to use as a brush gun or in very thick conditions. As a cartridge for hunting in the open plains or in wide open country though, it’s admittedly not the best choice.

Of course, since the .450 can be used in an AR-15, all you really need to use it is an .450 upper (hence you’re reading this article, right?) A .450 upper should be fully compatible with an existing 5.56 AR-15 lower, so if you already have an AR-15 there’s no need to buy an entirely new rifle since the new upper receiver will be your only necessity.

The .450 Bushmaster will even work with 5.56 magazines, although only theoretically. This means that there are some 5.56 magazines that it will likely work just fine in and others that it may not, depending on the brand. Users report having more issues with the metal GI-style STANAG magazines than polymer magazines such as Lancer or Magpul.

It’s up to you to test .450 Bushmaster rounds in your magazines to confirm function. Alternatively, you can always use magazines that are made for the .450 Bushmaster as well. If you do go with 5.56 magazines, however, for reference you can fit 7 rounds of .450 Bushmaster in a 20 round 5.56 magazine and 11 rounds in a 30 round 5.56 magazine. Again, it’s your responsibility to confirm proper function in the magazines.

In many ways, you can think of the .450 Bushmaster as being a larger rifle version of the .45 ACP. It generates a respectable amount of power and energy at closer ranges, and within a range of two hundred to two hundred fifty yards it can be devastating against large dangerous game and drop them on one shot.

What Is The Upper Receiver of a .450 Bushmaster?

The upper receiver of an AR-15 consists of the action, bolt, and the firing mechanism. It also receives the barrel and the stock. In other words, it’s the component of the firearm that is the most directly involved with firing the rounds.

The lower receiver, in contrast, contains the magazine well, the grip, the firing pin, and the trigger.

When shopping for upper receivers, you will hear of the terms ‘stripped upper receiver’ and ‘complete upper receiver’ being thrown around. A complete upper receiver is exactly what: a truly complete upper receiver with all of the necessary components already installed. You can attach it to the lower receiver of your AR-15, and assuming that the lower receiver is complete as well, you can begin firing when the weapon is loaded.

A stripped upper receiver means that the receiver does not have all of the components installed yet, and therefore may lack necessary components such as the barrel or the dust cover or forward assist and so on.

Why would you go with a stripped upper receiver when the complete one is already good to go out of the box? The answer is customization. If you want to select every component that goes into your AR-15 yourself, you should get a stripped upper receiver that consists of only the frame to the receiver itself without the components. Gunsmithing will not be required for assembling your upper receiver if you know what you’re doing and don’t buy parts that require special fitting.

A complete upper receiver will be a better choice if you don’t want to mess around with assembling your receiver yourself and just want everything ready to go when you buy the whole thing at once.

Later in this article, we will feature both stripped and complete upper receivers for you to choose from.

Buyer’s Guide To Finding The Best .450 Bushmaster Uppers For 2020

These are the most important factors to consider when you are looking for a new upper receiver for your .450 Bushmaster AR-15 rifle:

Durable Materials

The two primary materials that AR-15 companies choose when building their upper receivers are aluminum and steel. Aluminum is the lighter weight of the two, and while it’s not as durable, it’s still respectably tough and can last you a lifetime of hard use.

Keep in mind, the .450 Bushmaster is designed for hunting, which means that you’re not likely to shoot it as much as if you were to use the rifle primarily for tactical training where you would have extended firing sessions. If you were going to shoot a lot of rounds downrange consistently, then steel would definitely be the better option. Otherwise, for hunting purposes aluminum will work just fine.

When it comes to steel, you have plenty of different durable options (such as chrome moly, stainless steel, etc.) but the expense will come at added weight. This is great to hold up under extended firing sessions, but when hunting out in the woods where you’ll just be trekking over rough terrain with the rifle slung over your shoulder all day,

Rust and Corrosion Resistant Finish

Applying special finishes to the outside of your upper receiver, regardless of whether it is built out of steel or aluminum, will always intrinsically increase the durability and rust and corrosion resistance of the receiver.

Examples of finishes that are more rust and corrosion resistance include stainless, chrome lining, a hard anodized finish, or cerakote.

Barrel Length

The most common barrels for the .450 Bushmaster AR-15 are 16 inches, 18.5 inches, and 20 inches. Out of these, 16 inches offers you the most maneuverability but less bullet velocity and performance. Recoil is also slightly worse out of the 16 inch version. 18.5 inch can offer you a good balance between the two, but are actually the least common out of the three. If low recoil is important to you, our advice would be to get a .450 Bushmaster muzzle brake and attach it to your barrel.

It’s up to you to decide if you want to prioritize having a more maneuverable rifle in tight brush or a longer and more unwieldy rifle that will offer slightly better bullet performance.

Ease of Installation

As was noted previously, you shouldn’t need a gunsmith to assemble the components in your upper receiver, but you will as long those components are going to require special fitting and adjusting that only a professional and competent gunsmith can do for you.

Take note that many companies will claim that their components will drop right in without requiring a gunsmith’s services, when in reality it will require a considerable amount of work to get the parts in and you’ll end up hiring a gunsmith anyway.

There are two ways to ensure that the components will indeed be easy to install: if they are mil-spec (meaning that they should indeed just drop right in), and if users online consistently report that they could drop in the components easily.


Last but not least, this is likely going to be a factor into your considerations too. Stripped upper receivers will always cost less than complete upper receivers, but keep in mind that you’re still going to need to buy the additional components on your own and those will add up, so it doesn’t necessarily mean that you’re saving money when you with a stripped upper.

For a quality stripped upper receiver, you can expect to pay in the sixty to hundred dollar range, and for a complete upper receiver you’re most likely going to need to spend several hundred dollars. But remember, you can use a 5.56 lower for your .450 Bushmaster, so if you already own an AR-15 in 5.56 you won’t have to buy an additional lower receiver if you don’t want to.

The 3 Best .450 Bushmaster Uppers

Now that we’ve gone through the basics of the .450 Bushmaster and the top qualities to look for in an upper receiver for one, here are our top three picks for .450 Bushmaster Uppers:

Radical Firearms Complete .450 Bushmaster Upper Receiver

Radical Firearms Complete .450 Bushmaster Upper Receiver

The Radical Firearms Complete .450 Bushmaster Upper Receiver is exactly what the name suggests: a complete upper receiver that comes with literally everything you need right out of the box. Available in both twenty inch and sixteen inch barreled versions, the Radical Firearms Complete Upper comes with an M-Lok Hybrid rail with four different Picatinny sections located around the circumference of the forend.

This upper also comes with a .936-inch gas block journal, a charging handle, forward assist and dust cover, and an HBAR-contoured barrel. The twenty inch barreled version has a rifle length gas system, while the sixteen inch barreled version has a mid-length gas system as opposed to a carbine length one in order to get better performance out of the .450 Bushmaster round.

Radical Firearms Complete .450 Bushmaster Upper Receiver muzzle

Radical Firearms does charge a fairly high price for this upper receiver, but keep in mind that you are getting literally everything that you need all in the same package.

Overall, if you’re looking for a complete .450 Bushmaster upper receiver that has literally everything you need right out of the box, the Radical Firearms Complete Upper is a superb way to go. If you want to customize your upper receiver right out of the box, however, then this won’t be the best choice because it’s already fully assembled.

See on Brownells

  • HBAR contoured barrel
  • Excellent performance
  • 20” and 16” barreled versions are both available
  • Comes with M-Lok hybrid rail with Picatinny sections
  • Comes with forward assist and dust cover
  • Expensive

Aero Precision Assembled XL .450 Bushmaster Upper Receiver

Aero Precision Assembled XL .450 Bushmaster Upper Receiver

If you’re looking for mostly assembled upper receiver then you’ll want to take a look at the Aero Precision Assembled XL Upper Receiver. This receiver comes with far more features than a stripped upper receiver does, but is still lacking on other things such as a barrel or dust cover, so you will need to add those yourself.

The Aero Precision Assembled XL is built out of a very durable 7075 T6 aluminum material and has an anodized matte black finish applied to the surface of it, which makes it very rust and corrosion resistant. It is fully compatible with standard AR-15 parts, and has a larger port door opening in order to handle the larger .450 Bushmaster rounds and eject them reliably.

Aero Precision Assembled XL .450 Bushmaster Upper Receiver

If you’re looking for an upper receiver that comes with some of what you need but still is lacking in a few other features so you can customize it, the Aero Precision Assembled XL will be a good option. Overall, this is an excellent value for an AR upper receiver.

See on Brownells

  • Leaves you with plenty of customization options
  • Hard Anodized Finish
  • Overall good value
  • Durable 7075 T6 aluminum construction
  • Built to mil-spec standards
  • Larger port door opening ensures better reliability
  • Not a complete upper receiver, so not the best choice
  • Dust cover and forward assist not included (but can be installed yourself)

Aero Precision Stripped XL .450 Bushmaster Upper Receiver

Aero Precision Stripped XL .450 Bushmaster Upper Receiver

The stripped down version of the Assembled XL receiver from Aero Precision is the Stripped XL receiver. As such, it likewise comes with a durable 7075 T6 aluminum build and a hard coat anodized finish for solid rust and corrosion resistance. The entire receiver is built to mil-spec standards with normal M4 feed ramps.

The poor door opening to this receiver has also been enlarged in order to better accommodate the .450 Bushmaster rounds and promote better feeding and ejection.

Aero Precision Stripped XL .450 Bushmaster Upper Receiver

The Aero Precision is built out of high quality materials, but you’ll need to buy the remainder of the components that it does not come with separately and then assemble a complete upper yourself. If you’re not willing to do that, you should look for a complete upper receiver like the Radical Firearms option we just looked at previously.

See on Brownells

  • Allows full customization
  • Larger port sized door to ensure proper ejection
  • Hard coat anodized finish for superior corrosion resistance
  • Durable 7075 T6 aluminum construction
  • Overall great value
  • Not a good choice if you don’t want to mess with purchasing and assembling the separate upper receiver components yourself

Wrap Up

Buying a high quality .450 Bushmaster upper receiver is exactly the way to upgrade your AR-15 to give it added firepower so it can be used to bring down large and dangerous game within reasonable distances.

When looking for an upper receiver for your .450, any one of the three that we have covered here today will be a high quality option, or alternatively you can go with any other receiver that has each of the qualities we have covered here today.

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