AR57 AR-15 Generation 2 A3 Upper Receiver Assembly 5.7x28mm FN 16" Barrel
- Upper Receiver: A3 Flat-Top
- Barrel Length: 16"
- Barrel Contour: Fluted, heavy
- Barrel Material: 4140 Chrome Moly Steel
- Muzzle Thread Pattern: 1/2"-28
- Chrome Lined: No
- Barrel Finish: Parkerized
- Twist Rate: 1 in 8.5"
- Chamber: 5.7 x 28mm FN
- M4 Feed Ramps: N/A
- Muzzle Device: A2 Flash Hider
- Gas System Length: Carbine
- Gas Block Diameter: 0.750"
- Handguard: Free-Float Quad Rail
- Sights: None
- Bolt Carrier Assembly Included: Yes
- Bolt Carrier Type: N/A
- Extras: Single Rail Gas Block
Please Note: Installation of AR-15 upper assemblies with certain features including, but not limited to: flash hiders, bayonet lugs, and threaded muzzles may violate state and/or local laws.
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