Are you looking to put together your own AR-15 in .450 Bushmaster or upgrade an existing one to the round?
Either way, you’ve come to the right place. Your .450 Bushmaster rifle is only as good as its upper receiver. So, with that in mind, buying one with quality is just as crucial as learning how to shoot it.
In this article, we’re going to dive into what makes the .450 Bushmaster such a great round. We will also review the top components and features that your upper receiver needs to have. More importantly, we will take a look at the best .450 Bushmaster upper receivers on the market, both stripped and complete.
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Quick Summary of the Best .450 Bushmaster Uppers
|Aero Precision XL Assembled Upper|| ||$97 Shop NowClick to read my review|
|Aero Precision XL Stripped|| ||$80 Shop NowClick to read my review|
|San Tan Tactical-15 Big Bore Billet Assembled|| ||$246 Shop NowClick to read my review|
|American Tactical .450 Bushmaster 16|| ||$389 Shop NowClick to read my review|
|Bushmaster .450 20|| ||$616 Shop NowClick to read my review|
|Next Level Armament .450 Bushmaster 16|| ||$750 Shop NowClick to read my review|
The .450 Bushmaster was born from the concept of firearms legend Jeff Cooper. Cooper was a fan of the AR-15 design but not the .223 Remington or 5.56x45mm NATO cartridges. He was not satisfied with the round when it came to big game hunting.
Cooper’s idea was to develop a bigger round that could still use the AR-15 platform and magazines. As he said, he wanted a “Thumper” round to be fired out of the AR-15. LeMag Firearms heard Cooper and developed the .45 Professional round. Hornady became the manufacturer and so the .450 Bushmaster round was officially born.
Why Go With The .450 Bushmaster?
The .450 Bushmaster is designed with one purpose in mind: hunting. Like the .45-70 Government round, it takes down big game animals in North America within 250 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. Though, admittedly, it’s not the best choice for hunting in the open plains or wide-open country.
Compatibility With 5.56 Components
Since the .450 can be used with an AR-15, all you really need to use it is a .450 upper (hence you’re reading this article, right?) A .450 upper should be 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. Just get a new upper receiver and you’re good to go.
The .450 Bushmaster will even work with 5.56 magazines, although only theoretically. This means that there are some 5.56 magazines that the .450 will likely work just fine with. Still, there will be others that 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 the .450 Bushmaster rounds in your magazines to confirm function. Alternatively, you can always use magazines that are made for the .450 Bushmaster as well.Â
The 5.56 are smaller so it will fit lesser rounds when you put .450 in it. 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, within 200 to 250 yards. Without a doubt, it can be devastating against large and dangerous games and drop them in one shot.
What Is The Upper Receiver of a .450 Bushmaster?
The upper receiver of an AR-15 consists of the action, bolt, and 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. It also houses the grip, the firing pin, and the trigger.
Upper Receivers: Stripped vs Complete
What’s the difference between stripped upper receivers and complete upper receivers? You might have heard of these terms being thrown around when shopping for one.
A stripped upper receiver means it does not have all the components installed yet. It may lack necessary components such as the barrel, dust cover, or forward assist so it still needs a lot of work.
A complete upper receiver is exactly what it’s called. Since it’s complete, it already has all the necessary components installed. You can attach it to your AR-15’s lower receiver, and assuming that it is complete as well, you can readily load and use it.
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 option. It consists of only the frame and the receiver itself without the other components.
You won’t need gunsmithing for assembling your upper receiver if you know what you’re doing. Also, just make sure not to buy parts that need special fitting and you will do just fine.
A complete upper receiver will be a better choice if you don’t want to mess around with assembling the receiver. It is the one for you if you want everything ready to go when you buy the whole thing at once.
Buyer’s Guide to Finding the Best .450 Bushmaster Uppers for 2021
Below are the things to consider when looking for a new .450 Bushmaster upper receiver.
The most common materials used for upper receivers are aluminum and steel. Between the two, aluminum has the advantage of being lighter. While it’s not as durable as steel, it’s still respectably tough and can last you a lifetime of hard use.
Keep in mind that the .450 Bushmaster is a hunting round. That means you’re not likely to shoot it as much if you were to use the rifle for tactical training. Extended firing sessions are rare for this round’s purpose. If you were to shoot a lot of rounds consistently, then steel would definitely be the better option. Otherwise, for hunting purposes, aluminum will work just fine.
You have plenty of durable options with steel such as chrome-moly and stainless steel. This is great to hold up under extended firing sessions. Though, the expense will come at an added weight. When hunting out in the woods, most of the time you’ll be trekking over rough terrain with the rifle slung over your shoulder all day, so that’s also something to consider.
Rust and Corrosion Resistant Finish
Regardless of the material, your upper receiver always gets better with special finishes. Aside from intrinsically increasing durability, it also makes the receiver rust and corrosion-resistant.
Rust and corrosion-resistant finishes include stainless, chrome lining, a hard-anodized finish, or cerakote.
The most common barrels for the .450 Bushmaster AR-15 are 16 inches, 18.5 inches, and 20 inches. The 16 inches offers the most maneuverability but less bullet velocity and performance. Recoil is also slightly worse on this version.
An 18.5-inch barrel length offers a good balance between the other two. Yet interestingly, it’s the least common 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 one that will slightly offer better bullet performance.
Ease of Installation
As noted before, you shouldn’t need a gunsmith to assemble your upper receiver. Many companies will say that their components will drop right in without a gunsmith’s help. Still, some parts will need a considerable amount of work to install and you’ll end up hiring a gunsmith anyway.
There are two ways to ensure that the components will indeed be easy to install. The first is if they are mil-spec or that they meet the military standard specification. If they do, the parts should indeed just drop right in. Another thing we can do is check the feedback of other users online. That way, we can get honest reviews on the experience of others.
Last but not least is cost. This is likely going to be a factor in your considerations too. Stripped upper receivers will always cost less than complete upper receivers. However, keep in mind that you’re still going to buy the other components on your own. Those will add up, so it doesn’t necessarily mean that you’re saving money with a stripped upper.
For a quality stripped upper receiver, you can expect to pay in the 60 to 100 dollar range. Meanwhile, you’re most likely going to need to spend several hundred dollars for a complete one.Â
A good thing to remember is that you can use a 5.56 lower receiver for your .450 Bushmaster. So if you already own an AR in 5.56, you won’t have to buy a new lower receiver if you don’t want to.
The 6 Best .450 Bushmaster Uppers
Now that we’ve gone through the basics of the .450 Bushmaster, it’s time to check the best .450 Bushmaster Uppers.Â
Aero Precision XL Assembled Upper
The Aero Precision Assembled XL Upper Receiver is a partly complete upgrade. It comes with far more features than a stripped upper receiver. Still, it lacks other components such as a barrel or dust cover, so you will need to add those yourself.
The Aero Precision Assembled XL is made of very durable 7075 T6 aluminum material. It has an anodized matte black finish making it very rust and corrosion-resistant. It goes well with standard AR-15 parts. Also, the larger port door fits the .450 Bushmaster rounds and ejects them like clockwork.
If you’re looking for an upper receiver that has some parts but still gives room for customization, then this is it. As a whole, the Aero Precision Assembled XLÂ is an excellent value for an AR upper receiver.
- 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
- Needs more work with additional components
- Dust cover and forward assist not included (but can be installed yourself)
Aero Precision XL Stripped Upper
The Aero Precision Stripped XL receiver needs more customization than the version above. Still, it comes with a durable 7075 T6 aluminum build. It also has 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 was enlarged to better accommodate the .450 Bushmaster rounds. This feature also promotes better feeding and ejection.
The Aero Precision upper is made of high-quality materials, but you’ll need to buy the rest of the components. After that, you have to assemble the complete upper yourself. That’s a great thing if you want to fully customize your build. However, if you don’t have time to do all this work, this stripped version will not be very ideal.
- Allows full customization
- Larger port sized door ensures proper ejection
- Hard coat anodized finish for superior corrosion resistance
- Durable 7075 T6 aluminum construction
- Overall great value
- Needs separate purchase of other components
- Not the best choice if you don’t want to assemble it yourself
San Tan Tactical-15 Big Bore Billet Assembled Upper
The San Tan Tactical-15 Big Bore Billet is made for large cartridges like the .450 Bushmaster. It can endure the no-nonsense recoil that comes with this round, as well as those of .458 SOCOM and even 50 Beowulf. It also has an enlarged ejecting port to easily pass spent big-bore cases.
The 7075-T651 aluminum-made upper comes with truss pockets to ensure durability and strength. This design also helps distribute recoil tension throughout the receiver. Though it is a billet receiver, this one is actually significantly light at only 8 ounces.
The San Tan Tactical-15 Big Bore Billet upper has a hard anodized coating. It was also patterned to mil-spec standard to ensure compatibility with other parts. Since it’s already assembled, it comes with the forward assist and ejection port cover. Still, you still have to look for a compatible barrel, handguard, and other components.Â
The fact that it already has some of the parts means you don’t have to start from scratch. All in all, it is a quality upper receiver that won’t disappoint.
- Designed to last
- Specifically made for big-bore rounds
- Already assembled with forward assist and ejection port cover
- Compatible with most AR-15 parts and accessories
- Not a complete upper receiver
American Tactical .450 Bushmaster 16″ Complete Upper
The American Tactical .450 Bushmaster is a complete upper receiver. It is made of forged 7075-T6 which has the durability and strength needed to house the .450.
Attached to the main receiver is a 16-inch barrel with a 1:24″ twist rate. It has a superior nitride finish that makes it more durable and resistant to the elements. This upper makes use of a carbine-length gas system. All these are enclosed in a free-float handguard for accuracy. Also, the key-mod rail system has a big room to accommodate optics and other accessories.
Along with the barrel, this receiver also has the bolt carrier group and charging handle. With a large-caliber cartridge comes greater muzzle flip, so it helps that it also comes with an A2-style compensator.
Even if it is a complete upper receiver, it may still need some adjusting out of the box. A little fine-tuning of the hardware here and there will do the trick. Some find it ready to use but others also have their own preferences. Whichever you are, this upper can just ride with the lower receiver in no time.
The ATI .450 Bushmaster complete upper receiver saves the hassle of building one from the ground up. The $599.95 MSRP is a great price point since it already comes with everything you need to complete your AR build.
- Excellent aesthetics
- Free-float handguard increases accuracy and stability
- Great inclusions
- Good value for the money
- May need some adjustments out of the box
Bushmaster .450 20″ Barrel Flat-Top Complete Upper
If you’re looking for an upper with a longer barrel, then Bushmaster’s flat-top complete upper receiver would be an ideal choice. The 20-inch barrel brings higher velocity while minimizing muzzle blast. It has 1:24″ rifling and is chrome-lined for durability and easy maintenance.
This flat-top upper gives you room for the easy addition of optics and other accessories. The handguard is made of aluminum to stand against the burning power of the “thumper.” Since it’s free-floating, it leaves the barrel stable and accurate despite external modifications.
Although most, if not all, choices on the market have the usual black finish, we can’t deny the fact that this Bushmaster upper receiver looks real sleek and impressive with all its monochrome glory. This complete package comes with the bolt carrier assembly and a magazine. It also has a threaded barrel for you to attach your muzzle device of choice.
At six pounds, this upper receiver weighs more and can handle recoil better than those with shorter barrels. That said, it may not be as handy and can become a challenge to transport. In the end, it would still depend on the purpose you’re buying this upper for.
- Good-looking system
- Includes the bolt carrier group and a magazine
- Longer barrel adds weight which helps with recoil
- Compatible with any mil-spec lower
- Not as handy as uppers with shorter barrels
Next Level Armament .450 Bushmaster 16″ Complete Upper
The Next Level Armament .450 Bushmaster complete upper receiver is another great option if you’re planning to enter your AR-15 into the hunting scene. There’s no need to buy individual parts as it comes with all the needed upgrades out of the box.
The forged upper receiver has a 16-inch barrel with a 1:24″ twist rate. At $750, this is obviously the most expensive upper receiver on this list. Nonetheless, it more than makes up for it as it already comes with all the parts you’ll need for a complete AR-15 upgrade.
This receiver includes a carbine-length gas system, bolt carrier group, and charge handle. It also comes with an M-Lok handguard, muzzle brake, spring, and a five-round magazine. Firing the beast that is the .450 Bushmaster is more manageable with the ambidextrous charging handle and muzzle brake. There’s also the tough buffer spring to counter the effects of recoil.
Getting the NLA .450 Bushmaster complete upper is like doing all the shopping at once. Not only does it save time and effort, but it also assures that the parts fit together and go well with each other.
As NLA says, “Why pay less for inferior parts and pay more to upgrade later?” It pays to invest in a trusty upper in the long run. So, if you are looking for a premium upgrade, this is the upper receiver to have.
- Ambidextrous charging handle
- Complete with all the needed parts for a .450 upgrade
- Compatible with any standard AR-15 lower
- Comes at a higher price
The .450 Bushmaster isn’t considered a thumper round for no reason. It has the power and punch to take down deer and some large game without a hitch. When looking for an upper receiver for your .450, any one of the six we have covered will be a high-quality option.
For our best stripped/assembled upper receiver pick, we’ll go with Aero Precision XL Stripped for full customization. The American Tactical .450 Bushmaster 16″ Complete would be our best-budget complete upper receiver pick. It’s reliable and offers great value for the money.Â
Are you looking for more .450 Bushmaster accessories? Check out our best .450 muzzle brakes list to see the best options on the market. Also, if you’re eyeing for another upgrade, check out our top .458 SOCOM uppers.