Custom: Core SpecificationsAction: Semi-Automatic, Direct Impingement Gas SystemCaliber: 5.56 x 45 mm NATO (also accepts .223 Remington)Barrel Length: 16 inches (M4 or government profile)Twist Rate: 1:8 inchesBarrel Material: 4150 Chrome Moly Vanadium (CMV), Nitride or Parkerized finishOverall Length: 32.5 inches (collapsed) to 36.125 inches (extended)Weight: ~ 6.5 - 7 pounds (unloaded)Hardware & FurnitureUpper & Lower Receivers: Forged 7075-T6 AluminumReceiver Finish: Type 3 Hard Coat Anodized (Black)Handguard: A2 plastic handguard Carbine-length, low-profile or railed standard gas blockTrigger: Anderson Stainless Steel or Mil-SpecGrip: A2 Style pistol gripStock: 6-position M4 carbine telescoping stockMuzzle Device: A2 Flash Hider (1/2 x 28 thread pitch)