DPMS AP4 is their M4-configuration AR-15 with a four-position collapsible Magpul CTR stock, M4 handguard, and a 16-inch M4-profile chrome-lined barrel. Positioned between the Oracle and the Recon in the DPMS product hierarchy. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 5.56x45mm Capacity: 30 Year introduced: 2009, USA Weight: 6.6 oz Overall length: 32.5" Status: Active Intended use: Home Defense, Patrol, Range