Bushmaster® 20″ .450 BUSHMASTER Barrel

Description

The .450 Bushmaster cartridge delivers a trajectory and energy profile that makes it a capable choice for medium-game hunters across the United States, particularly in states with straight-wall cartridge regulations. For AR-style platform builders, the 20-inch barrel length offers a balance of velocity retention and maneuverability that suits both stand hunting and still-hunting in dense cover. This barrel from Bushmaster provides a foundation for a build that can reliably take deer, hogs, and black bear at typical hunting distances.

What This Product Is and Who It’s For

This is a factory-manufactured, 20-inch .450 Bushmaster barrel designed for use with AR-15 style upper receivers and bolt carriers that are compatible with the .450 Bushmaster cartridge. It is intended for shooters who are building or upgrading a dedicated upper assembly for hunting applications where the .450 Bushmaster’s straight-wall case is legal, such as in Ohio, Michigan, Indiana, and other states with similar restrictions. The barrel is also suitable for shooters who want a hard-hitting, low-recoil option for large feral hog control or for those who simply prefer a larger caliber in their AR platform for reasons of terminal performance. While it can be used for target shooting and plinking, its primary design purpose is for hunting medium game at ranges under 250 yards. This is not a barrel intended for high-volume tactical training or competition use; it is a hunting and field-use component.

Key Specifications

• Caliber: .450 Bushmaster
• Barrel Length: 20 inches (measured from bolt face to muzzle)
• Twist Rate: 1:24 inches (standard for stabilizing .450 Bushmaster projectiles in the 250-300 grain range)
• Barrel Material: 4150 Chrome Moly Vanadium steel, a common specification for AR barrels that balances durability and weight
• Finish: Manganese Phosphate (Parkerized), providing corrosion resistance and a non-reflective matte appearance
• Gas System: Not applicable. The .450 Bushmaster is a straight-wall cartridge that operates as a direct blowback system; this barrel does not have a gas port or gas block journal.
• Muzzle Threading: 11/16-24 TPI, a standard thread pitch for .450 Bushmaster muzzle devices
• Barrel Profile: Heavy/Government profile, adding mass for heat dissipation and stability during strings of fire
• Weight: Approximately 3.2 pounds (depending on exact contour and finish)
• Sights: No iron sights included; the barrel is designed for use with a scope or red dot sight mounted to the upper receiver
• Chamber: SAAMI-spec .450 Bushmaster chamber, headspaced at the factory
• Gas Block Journal: Not present; this barrel is for blowback operation only
• Made in: United States

Feature Deep-Dive

The 20-inch barrel length is a deliberate choice for the .450 Bushmaster cartridge. A 20-inch barrel allows the slower-burning powders used in .450 Bushmaster loads to achieve near-maximum velocity before the projectile exits the muzzle. In practical terms, this means you can expect muzzle velocities in the range of 2,200 to 2,400 feet per second with 250-grain projectiles, depending on the specific ammunition used. This velocity window is sufficient to deliver reliable expansion and energy transfer on deer-sized game out to 200 yards, while the heavy bullet weight maintains momentum for deeper penetration on larger animals like hogs or black bear.

The barrel is constructed from 4150 Chrome Moly Vanadium steel, which is a step up from standard 4140 steel. This alloy includes vanadium, which refines the grain structure of the steel and increases its tensile strength and wear resistance. For a hunting barrel that may see exposure to moisture, mud, and repeated cleaning, 4150 steel provides a longer service life before throat erosion or accuracy degradation becomes noticeable. The manganese phosphate finish further aids in corrosion resistance, as the porous nature of the finish holds oil and lubricants, creating a protective layer against rust and oxidation.

The 1:24 twist rate is the SAAMI standard for .450 Bushmaster barrels. This slower twist rate is specifically chosen to stabilize the relatively short, heavy bullets typical of the .450 Bushmaster, such as 250-grain Hornady FTX or 300-grain hard-cast projectiles. A faster twist rate, like 1:16 or 1:12, would over-stabilize these bullets, potentially causing keyholing or reduced accuracy. The 1:24 twist ensures that the bullet exits the barrel with enough spin to maintain a stable flight path without excessive gyroscopic drag, which is why this barrel can produce consistent groups with factory ammunition.

The barrel uses a heavy contour, often referred to as a Government profile. This profile adds approximately 0.5 to 0.8 pounds of weight compared to a lightweight or pencil profile barrel of the same length. The additional mass serves two purposes: it reduces felt recoil by absorbing some of the impulse from the .450 Bushmaster’s substantial push, and it helps maintain accuracy during successive shots by acting as a heat sink. In a hunting scenario where you might fire two or three rounds at a group of hogs, the heavy profile keeps the barrel from heating up quickly, which can cause point-of-impact shifts.

The barrel is threaded 11/16-24 TPI, which is the standard thread pattern for .450 Bushmaster muzzle devices. This allows you to install a muzzle brake, compensator, or a suppressor that is rated for .450 Bushmaster pressures. Because the .450 Bushmaster operates at lower pressures than 5.56 NATO (approximately 38,500 PSI vs. 55,000 PSI), many .45-caliber suppressors can be safely used with this barrel, provided they are rated for the cartridge. The threading is cut to SAAMI specifications, so aftermarket muzzle devices from manufacturers like Witt Machine, SilencerCo, or Yankee Hill Machine should thread on without issue.

Because this is a blowback-operated barrel, there is no gas block journal, gas port, or gas tube required. This simplifies the build process: you only need to install the barrel into the upper receiver, torque the barrel nut to spec, and attach a handguard that fits the barrel nut thread pattern. The lack of a gas system also means there are fewer parts to clean or maintain, which can be an advantage for a hunting rifle that may sit in a safe for months between uses. However, it does mean that the bolt carrier group must be specifically designed for .450 Bushmaster blowback operation, typically with a heavier carrier or a tungsten buffer to control bolt velocity.

Ideal Use Cases

Medium-Game Hunting: This barrel is primarily designed for hunting deer, hogs, black bear, and other medium game in states that allow straight-wall cartridges. The 20-inch length provides sufficient velocity for ethical shots out to 200 yards, and the heavy bullet weight ensures penetration through shoulder bones and thick hide. For stand hunting or still-hunting in wooded areas, the 20-inch barrel is long enough to maximize velocity but short enough to maneuver in a tree stand or ground blind.

Feral Hog Control: The .450 Bushmaster’s combination of heavy bullet weight and moderate velocity makes it effective for dispatching feral hogs, which can be tough and require deep penetration. The 20-inch barrel allows for the use of heavier 300-grain loads that can break through a hog’s shield (the thick cartilage on the shoulder) and reach vital organs. In situations where multiple hogs are present, the AR platform allows for quick follow-up shots.

Target Shooting and Plinking: While not the primary intended use, this barrel can be used for recreational target shooting at ranges up to 200 yards. The recoil is noticeable but manageable, and the heavy barrel profile helps maintain accuracy for extended shooting sessions. Ammunition cost is higher than 5.56 or .223, so this is not a high-volume plinking option, but it is suitable for zeroing and practice.

Compatibility Notes

• Ammunition: This barrel is compatible with all SAAMI-spec .450 Bushmaster ammunition, including factory loads from Hornady, Federal, Remington, and Winchester. Reloaders should use .450 Bushmaster-specific dies and brass. Do not use 5.56 NATO, .223 Remington, or any other caliber in this barrel.
• Upper Receiver: This barrel is designed for use with AR-15 upper receivers that have a .450 Bushmaster-compatible bolt face. A standard AR-15 bolt carrier group will not work; you need a bolt specifically cut for the .450 Bushmaster cartridge.
• Magazines: Standard AR-15 magazines will not reliably feed .450 Bushmaster cartridges due to the larger case diameter. You must use dedicated .450 Bushmaster magazines, such as those from Lancer or ASC (Ammunition Storage Components). Typically, a 5-round magazine is used for hunting to comply with magazine capacity limits, but 7- and 10-round options are available.
• Muzzle Devices: The 11/16-24 TPI threading is compatible with most .450 Bushmaster muzzle brakes, compensators, and flash hiders. Suppressor compatibility depends on the suppressor’s bore diameter and pressure rating; confirm with the suppressor manufacturer that it is rated for .450 Bushmaster.
• Handguards: This barrel has a standard barrel nut interface, so it will work with most AR-15 handguards that use a standard barrel nut. Free-float handguards are recommended for best accuracy, but drop-in handguards will also function.

Frequently Asked Questions

1. Do you ship this barrel to all 50 U.S. states?
Yes, we ship to all 50 states. This barrel is a firearm component, not a firearm itself, so it is not subject to the same shipping restrictions as a complete firearm. However, we do not ship to addresses in states or localities that have banned the possession or transfer of AR-15 components, such as California (if the barrel is considered a “part” under local laws), New York, or certain municipalities. It is your responsibility to know your local laws before ordering. We ship via UPS or FedEx with adult signature required.

2. Do I need to have this barrel shipped to an FFL dealer?
No. Under federal law, a barrel is not a firearm and does not require transfer through a Federal Firearms Licensee (FFL). It can be shipped directly to your home address. However, some states or local jurisdictions may have specific regulations regarding the purchase or possession of firearm barrels. We recommend checking with your local law enforcement or a firearms attorney if you are unsure. We will not ship to P.O. boxes; a physical street address is required.

3. What ammunition is this barrel compatible with?
This barrel is chambered in .450