Models View all M4A1 - Bolt Carrier - Bolt Carrier - Firing Pin1 16 784 0 M4A1 - Bolt Carrier - Bolt - Extractor1 17 780 0 M4A1 - Bolt Carrier - Bolt Carrier- Bolt Cam Pin 20 817 5 M4A1 - Bolt Carrier - Bolt Carrier - Retaining Pin 10 596 0 M4A1 - Bolt Carrier & Key - Screw_HX-SHCS 0.164-32x0.25x0.25 11 448 0 M4A1 - Bolt Carrier - Bolt Carrier & Key - Key 22 887 2