This drop-in A3 upper will mount to virtually any standard AR-15 mil-spec lower receiver. With a velocity of 2200 FPS, the Hornady 250 Grain SST/FT bullet in the .450 Bushmaster "Thumper" is designed for all large North American game. Though not a long distance cartridge, accuracy has proved to be exceptional out to 200 yards with felt recoil similar to a 20 gauge shotgun. Tubular aluminum forends allow the barrel to free float from the nut forward, and chrome lining in both bore and chamber makes for long barrel life and easy cleaning.
This upper receiver assembly comes complete with a charging handle, forward assist, ejection port cover, bolt and bolt carrier assembly. The upper also features a versatile flat top for mounting optical devices or accessories.

Specifications:

- Upper Receiver Type: A3 Flat-Top
- Barrel Length: 20"
- Barrel Contour: Not listed by manufacturer
- Barrel Material: Chrome Moly Steel
- Muzzle Thread Pattern: 11/16"-24
- Chrome Lined: Yes
- Barrel Finish: Black Matte
- Twist Rate: 1 in 24"
- Chamber: 450 Bushmaster
- M4 Feed Ramps: Not listed by manufacturer
- Muzzle Device: Izzy Muzzle Brake
- Gas System Length: Rifle
- Gas Block Diameter: Not listed by manufacturer
- Handguard: Free Float
- Sights: None
- Bolt Carrier Assembly Included: Yes
- Bolt Carrier Type: N/A