Mad Chemist BCG 5.56/.300blk | MPI, HPT Bolt Carrier Group


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(3 customer reviews)

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High Pressure Tested (HPT)

  • Magnetic Particle Inspected (MPI)

  • Carrier machined from 8620 alloy, full auto profile, heat treated, Nitrided

  • Gas Key machined from 4130 chromoly steel alloy, heat treated and Nitrided

  • Bolt precision machined from 9310 alloy; carburized/case hardened, shot peened and Nitrided

  • 4140 Tool steel Extractor alloy, hardened and Nitrided

  • Extractor Pin, AMS6440/52100 Bearing grade steel retaining pin

  • 5 coil, Extractor Spring, ASTM Grade A 228 wire stock, stress relieved, Tensile Strength of 393,000 PSI Max, 80 Durometer Per AMS-R-6855 black insert

  • Extractor Spring O-Ring, Viton (FKM) Fluoropolymer Elastomer

  • S7 shock resistant tool steel alloy Ejector, hardened, shot peened per ASTM B851/SAE AMS2430, manganese phosphate

  • ASTM Grade A 228 wire stock Ejector Spring, heat treated, stress relieved – Tensile Strength of 376,000 PSI Minimum

  • Gas Rings, Steel Corrosion Resistant Per AMS 5906 – X3

  • Firing Pin, precision machined 8740 steel alloy, heat treated, precision ground & hard chrome plate

  • Firing Pin Retaining Pin, carbon steel ASTM A510, heat treated & manganese phosphate

  • Socket Cap Head Screw, steel, grade 4037 per ASTM, heat treated & manganese phosphate 2x

  • Gas Key is installed with Permatex aviation gasket sealer, torqued to 55-foot pounds, pneumatically steaked

  • Cam Pin, precision machined 4340 chromoly steel alloy, heat treated and Nitrided

Additional information

Weight 5 oz
Dimensions 6 × 4 × 2 in

3 reviews for Mad Chemist BCG 5.56/.300blk | MPI, HPT Bolt Carrier Group

  1. ajh6xd (verified owner)

    Best bag for your buck on a BCG

  2. Robert Pittman (verified owner)

    definitely a solid BCG and a good price. Makes a great replacement or a spare. If you don’t have a spare… well… fix it.

  3. Zach (verified owner)

    Sweet looking logo on a solid bcg.

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