Mil-Spec M4 Bolt Assembly, 5.56mm

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Sourced from a Tier 1 supplier of the M4A1 carbine, this 5.56mm complete M4 Bolt Assembly is manufactured to the highest of military standards. They are off the same production line as Bolt Assemblies paired with Bolt Carriers found in carbines throughout the entire Department of Defense, these components are both high quality and highly reliable.

This M4 Bolt is made from Carpenter 158 and features a Mag Phosphate coating. All bolts have been high pressure tested (HPT) and mag particle inspected (MPI), exceeding the MIL-spec standard. Geissele also utilizes the latest revision extractor spring, O-ring and insert, which maximizes the reliability of the bolt carrier group. This ensures positive ignition and extraction of all types of ammunition, including military surplus ammunition known to have hardened primers.  



This M4 Bolt Assembly includes the following:

  • M4 Bolt (Carpenter 158, Mag Phosphate, HPT/MPI)
  • Firing Pin
  • Retaining Pin
  • Cam Pin


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