Updated 02/22/2022 Updated 2/22/2022. Want to get into big-bore ARs? The big-bore brute packs a lot of punch at moderate distances and is a proven venison catcher, if you’re up to its fairly strong recoil. It also has a very expensive appetite. Factory ammunition is not cheap. The.450 Bushmaster is a great addition to any gun collection, even if you live in the great north woods. The.450 Bushmaster is a great addition to any gun collection. It allows you to fire 250-plus-grain projectiles out of an AR-15. You don’t need a lower if you already have one. All you need is a.450 Bushmaster top to make it work. Modularity is great! Although we won’t go into detail here, it’s worth taking the time to explain the differences between Bushy and regular 5.56..450 Bushmaster upper Inside OutSome caliber conversions can be more complicated than others. That’s just how life works. Imagine you were a handy smith working with AR-pattern rifles, and that you were converting parts rather than a complete upper. This is just an example. The barrel would be the only part that would need to be replaced if you wanted to go from a 5.56 NATO rifle to a.300 Blackout. The uppers are completely seamless between the cartridges. This makes sense because the Blackout is a 5.56 NATO case. It’s more complicated and dramatic to jump to.450 Bushmaster. You would need to address not only the barrel but also the bolt, and the upper receiver. To consistently kick your spent brass, the upper receiver must be mil-spec in every other way. This is how it works with any big-dog AR caliber (.458 Socom or.50 Beowulf), depending on the case length and diameter. If you’re a skilled tinker, you can use your Dremel to make a file and grind away, provided you are confident that you won’t “Bubba up” the job. There are also.450 Bushmaster upper receivers available, which come with precision-milled ejection ports. This is a good time to start exploring your options. San Tan’s Big Bore upper, made from billet aluminum, is lightweight and not too heavy. It also features a number design enhancements that will ensure it will last the long-term, such as the upper’s truss pockets. MSRP: $260; santantactical.com
Obsidian ArmsA lightweight option, the Obsidian Arms OA-15C big bore upper is ideal to suit highly mobile builds. It weighs only 8.8 ounces. The upper is made from billet 7075T6 aluminum alloy and can withstand the punishment of the.450 Bushmaster as well as your personal abuse. It has an extended ejection port and a removable brass deflector. If you prefer a more sleek-looking upper, the upper is a great eye-catcher. MSRP: $175; obsidianarms.com
Aero Precision XLThose who have built their own ARs know that Aero is synonymous with quality, offering high-quality parts at affordable prices. The company’s.450 Bushmaster top, the AR15XL, is no exception. The XL is a solidly constructed forged aluminum receiver. It has the strength to handle big-bore monsters as well as the design specifications to ensure it runs smoothly. an enlarged port. The upper is plain-jane in appearance, but it performs well. MSRP: $114.99; aeroprecisionusa.com
Go Big! :Complete.450 Bushmaster UppersNext-Level Armament NLX450 BushmasterNext-Level Armament’s NLX450 Bushmaster Upper is tough and built to withstand the abuse this big round gives. The NLX450 includes a forged upper receiver, extra-strength Springco buffer Spring spring, and a durable DLC finish on the bolt carrier. Tromix, a well-respected brand in big-bore AR, also contributed some components. Tromix made the.450BM bolt and barrel. They are available in 16-inch and 18-inch configurations with carbine, mid-length gas systems or both. The upper includes an ambidextrous charging handle and MLOK handguard, as well as a Next Level “Unique” muzzle brake. Every NLX450 upper comes with a 5-round magazine, so you can start shooting immediately. MSRP: $852.12; nextlevelarms.com
Windham Weaponry.450 ThumperWindham Weaponry does it right. Its Thumper, a tribute to Col. Jeff Cooper’s Thumper concept, has everything you need from a.450 Bushmaster top. It includes a 16-inch chromemoly-vanadium barrel with heavy profile and chrome-lined bore. The bolt is made from Carpenter 158 steel, which is standard in high-quality AR builds. The AR has a carbine-length gas line. Windham has a shorter 13-inch aluminum handguard with M-Lok slots at three, six, and nine o’clock. It’s also free-floated, which ensures that barrel harmonics are preserved. The Thumper ships with an A2 Birdcage flashhider, but if you are sensitive to recoil, you will need a brake or compensator. The upper comes with a 5-round magazine that can feed.450 ammo. MSRP: $805; windhamweaponry.com
Radical Firearms.450 Bushmaster MHR. Radical Firearms is a company that shooters should be aware of. Options are a hallmark of Radical Firearms, as is the.450 Bushmaster uppers. The upper is available with a 16-inch or 20-inch barrel. This allows you to customize your shooting style. Both barrels are high-profile and finished with the Panzer brake by the company, making it easier to shoot big-bore cartridges. Radical equips the build with its HMR Handguard, a lightweight hybrid 15-inch option that has plenty of M-Lok slots at three to six and nine o’clock. The gunmaker uses top-end internals and an enlarged ejection port to ensure smooth cycling. MSRP: $669.95; radicalfirearms.com
Bear Creek Arsenal.450 Bushmaster Bear Creek Arsenal has a unique upper that will get you started in the caliber, without you having to pay a cent. The gunmaker’s 18 inch barreled.450 Bushmaster upper, also known as a Mama Bear, is agile but long enough to get more out of the cartridge. The barrel is heavy and has a thick profile. However, the fire tube adds weight and reduces recoil. Bear Creek also outfits the barrel in a flash hider. The upper features a 15-inch M-Lok compatible handguard that allows for plenty of room to accessorize. Bear Creek has a unique side-charging system for the upper that many people find attractive. Never fear lefties, it’s ambidextrous. MSRP: $244.99; bearcreekarsenal.comAdam Borisenko contributed to this article.NEXT STEP: Download Your Free Storm Tactical Printable Target Pack62 Printable MOA Targets with DOT Drills – Rifle Range in YARDSThis impressive target pack from our friends at Storm Tactical contains62 printable targetsfor rifle and handgun range use. Target grids and bullseye sizes can be found in MOA. Get Free Targets
