DPMS AR-15 Mil-Spec Firing Pin One Size. Specifications for DPMS AR-15 Mil-Spec Firing Pin: Manufacturer: DPMS Finish: Hard Chrome Caliber: .300 AAC Blackout 5.56x45mm NATO Gun Make: AR Platform Gun Model: AR-15 Package Contents: DPMS AR-15 Mil-Spec Firing Pin What firearm models does the manufacturer say DPMS AR-15 Mil-Spec Firing Pin is compatible with? The manufacturer says that DPMS AR-15 Mil-Spec Firing Pin is compatible with AR-15DPMS DP301143: AR-15 Mil-Spec Firing Pin One Size