SOLGW 5.56 Bolt Carrier Group 158 Carpenter SP/HPT/MPI | Sons Of Liberty Gun Works BCG


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(6 customer reviews)

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Big Tex Outdoors



  Sons of Liberty Gun Works Bolt Carrier Group HPT/MPI

  • Precision machined from Carpenter Technology No. 158 alloy,
  • Heat treated per mil-spec,
  • Shot peened per ASTM B851/SAE AMS2430S,
  • Vibratory tumbled
  • Individual high pressure/proof (HP)
  • Full Auto test fired as an assembly
  • Individual magnetic particle inspection ASTM E1444/E1444M (MP)
  • Markings deep laser engraved (SP=Shot Peened, HP=High Pressure Tested, MP=Magnetic Particle Inspection.)


  • Precision machined from 4340 tool steel alloy per SAE AMS6415T/AMS6484D (vs 4140),
  • Heat treated
  • Shot peen per ASTM B851/SAE AMS2430S.

Extractor Retaining Pin:

  • Precision machined and ground S7 Tool Steel
  • Heat treated per ASTM A681-08
  • Shot peened per mil-spec print
  • Manganese phosphate

Extractor Spring:

  • Tactical Springs/Sprinco 5 coil, ASTM Grade A401 Chrome Silicon wire stock
  • Heat treated
  • Stress relieved, Molybdenum-Disulfide infused
  • Cryogenic processed (all post winding)
  • Mil-spec black insert/synthetic elastomer extractor buffer (nitrile-butadiene, shore hardness 80+/-5 durometer per MIL-PRF-6855)


  • S7 Tool Steel
  • Heat treated per ASTM A681-08
  • Shot peened per Mil-Spec
  • Manganese phosphate

Ejector Spring:

  • Heat treated
  • Mil Spec

Gas Rings:

  • Standard stainless steel per Mil-Spec X3


  • Machined from AISI 8620 aircraft qualty alloy per ASTM A108/A322-13
  • Full auto profile
  • Heat treated
  • Carburized/strain relieved, hard chrome bore
  • Precision ground gas key interface
  • Sons of Liberty Battle Flag logo deep laser engraved
  • Manganese phosphate

Gas Key:

  •  Machined from 4130 chromoly steel alloy per ASTM A108/A322-13
  • Heat treated, hard chrome internal
  • Manganese phosphate
  • Permatex sealed
  • Grade 8  hex screws torqued and staked all per mil-spec

Cam Pin:

  • Precision machined 4340 chromoly steel alloy per SAE AMS6415T/AMS6484D
  • Heat treated/processed per mil-spec
  • Manganese phosphate
  • Solid film lubricant applied and cured per mil-spec

Firing Pin:

  •  Precision machined 8640 steel alloy
  • Heat treated/processed per mil-spec
  • Hard chrome plate

Firing Pin Retaining Pin:

  • Precision machined from 1038 carbon steel
  • Heat treated/processed per mil-spec
  • Manganese phosphate

Additional information

Weight 15.9 oz
Dimensions 1 × 1 × 1 in

6 reviews for SOLGW 5.56 Bolt Carrier Group 158 Carpenter SP/HPT/MPI | Sons Of Liberty Gun Works BCG

  1. zstovall84 (verified owner)

    As with all of the Sons Of Liberty parts I’ve ordered, this BCG is great. Quality and finish are great. The staking looks great. I have no doubt that it will be a good long lasting BCG. Even in a time of unprecedented orders SOLGW put out a great product and Big Tex got it to me very quickly! I definitely recommend SOLGW and Big Tex.

  2. Hunter Crumley (verified owner)

    Excellent. I’d expect nothing less from SOLGW. The finish is nice, staking is superb, and quality is what you’d expect from SOLGW. Head spacing is good to go on my SOLGW upper. Per usual, Big Tex shipping was supremely fast.

  3. Tony Dominguez (verified owner)

    Was recommended SOLGW bcg and was not disappointed in the quality right outta box 1k rounds and no issues so far.

  4. blairgarber (verified owner)

    Best builds start with the best barrel and BCG. With an SOLGW BCG Mil-Spec is just the starting point. You choose SOLGW for their quality, material standards, and testing of every BCG component. Pressure tested, MPI, properly heat treated and shot peened with no cutting corners. You can tell when you look at the carrier’s chrome bore and see the brass from the test firing on the bolt face, this thing was put together and tested right,. and they run like it!

  5. davidpaularmstrong (verified owner)

    Great product, great company to buy from. Thanks Big Tex!

  6. nathan0215 (verified owner)

    As usual, SOLGW delivers an outstanding product. All BCG components were spot on in spec and assembled excellently. Ordering from Big Tex was an absolute pleasure as well and will be sure to purchase again.

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