Chamber: 5.56 NATO. Barrel: 16" or 20". 4150V Chrome Moly Vanadium Steel, Nitride finish. Barrel Profile: A2 Style. Twist Rate: 1:7". M4 extension. Mid-length gas system, Low profile .750" gas block. Upper Receiver Style: M4 flat top with feed ramps. Handguard: PSA 13.5" Lightweight M-LOK Free Float Rail. Bolt Steel: Carpenter 158. Bolt Carrier Steel: 8620. Staked gas key. PSA AR-15 Enhanced Polished Trigger (EPT). Mil-spec buffer tube. Magpul MOE Carbine six-position collapsible stock. (1) 30-round magazine (where available by law). Backup Sights: Magpul MBUS. Length: 32". Values are for the PSA PA-15 16" M4 Nitride Carbine. Add 20% for the PSA PA-15 20" Nitride Rifle Length variant. SEE POLITICAL PANIC PRICING.