The Adams Arms P1 is an AR-15 with Adams Arms' patented micro-sized piston system — a short-stroke gas piston that replaces the standard DI tube without requiring a different handguard. The piston keeps carbon out of the receiver significantly better than DI while fitting within a standard AR profile handguard. Adams Arms also sells the piston system as an aftermarket conversion. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2013, USA Weight: 96 oz Overall length: 35" Status: Active Intended use: sporting, law_enforcement, tactical