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  • Midwest PX Enhanced AR15/M4/M16 Bolt Carrier Group

    We spec-ed this BCG to provide excellent function, reliability, and durability while not breaking the bank.

    Bolt: 9310 steel, shot-peened, individually MPI tested and stamped, case-hardened, phosphated
    Carrier: 8620 steel, chrome-lined, heat-treated, fully-shrouded firing pin, phosphated, full-auto rated
    Gas key: Chrome-lined, Grade 8 fasteners, Permatex No. 3 sealant, staked
    Extractor: S7 tool steel, heat-treated to 48-53C Rockwell, phosphated. Five-coil extra power extractor spring and black spring insert installed (four-coil enhanced spring and CRANE o-ring also included separately)
    Cam pin: 4340 steel, heat-treated, phosphated
    Gas rings: McFarland one-piece ($3.95 value)
    Free Upgrades: Midwest PX Enhanced Reliabillity Kit: Five coil extra power extractor spring (installed), black spring insert (installed), four coil enhanced extractor spring, black CRANE o-ring, 3mL bottle of Tactical Springs Machine Gunners Lube, the lube recommended by Midwest PX ($12.85 value)
    All phosphated parts are done to MIL-STD-171
    100% manufactured in the USA

    We selected 9310 as the material for the bolt as it is less brittle than Carpenter 158. 9310 steel is frequently used in high stress/load applications and makes for an excellent bolt due to the higher nickel content yielding a more malleable core which improves cracking resistance. Inclusion of various upgrades such as the gas rings, firing pin retainer, and extractor spring are designed to further enhance the reliability and function of our BCG.

    We opted to install the five-coil extra power extractor spring because of it's proven track history for reliable, consistent, and strong extraction. Both of the extractor springs we provide with these BCGs are manufactured from certified chrome silicon wirestock, not music wire. These springs are strong, consistent, and feature long duty cycles. You will need to replace the bolt before you have to replace the extractor spring due to fatigue. The five-coil extra power spring is pre-installed in our BCGs however we also include the four-coil enhanced spring and CRANE o-ring should the end user want a less aggressive extraction. Installation of the o-ring with the five-coil spring is neither necessary nor recommended and may lead to case rim wear.



    Available Options:

    Charging Handle:
    This product was added to our catalog on Thursday 21 February, 2013.