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AR-15 Bolt Carrier Groups in 5.56, 7.62x39, 6.5 Grendel & More

The bolt carrier group is the engine of the AR-15. AllGoOperators stocks AR-15 BCGs for 5.56/.223, 7.62x39, 6.5 Grendel, 6.8 SPC and .224 Valkyrie, .458 SOCOM and .450 Bushmaster, in phosphate, nickel boron and DLC finishes, plus side-charging and lightweight options. In stock from $64.99.

Shop By Caliber

Every Bolt Carrier Group, By Bolt Face

The bolt face must match the cartridge case head. We have sorted the catalog by caliber family so you order the right bolt the first time.

01

5.56 / .223 Bolt Carrier Groups

Fits 5.56 NATO, .223 Remington, .223 Wylde, 300 Blackout and .350 Legend. Choose the standard 5.56 BCG at $64.99, the slick nickel boron BCG, the HM Defense HMB with its monolithic bolt, the BCM full-auto profile in FDE, or the lightweight BCG with a Carpenter 158 bolt, Sprinco gas rings and a DLC finish.

5.56 .223 BCG Nickel Boron BCG HM Defense HMB BCG Full Auto 5.56 BCG FDE Lightweight BCG
02

Side-Charging Bolt Carrier Groups

Built for side-charging uppers. The side-charging BCG in 5.56 covers .223, 5.56, 300 BLK, .223 Wylde and .350 Legend, and we stock side-charging carriers for 7.62x39 and 6.5 Grendel as well.

5.56 Side Charging BCG 7.62x39 Side Charging BCG 6.5 Grendel Side Charging BCG
03

7.62x39, Grendel & 6.8 SPC

Larger case heads need larger bolt faces. Our 7.62x39 MPI BCG is magnetic particle iallgooperatorsted for the pressure of steel-cased ammo, and the .224 Valkyrie / 6.8 SPC BCG covers both cartridges with one bolt.

7.62x39 MPI BCG .224 Valkyrie / 6.8 SPC BCG 7.62x39 Parts
04

Big Bore

The .458 SOCOM / .450 Bushmaster BCG is cut for the large rebated rim these thumpers share. Pair it with the matching barrel and a heavy buffer.

.458 SOCOM / .450 Bushmaster BCG Buffer Kits & Parts
05

Complete the Upper

A BCG goes in alongside a charging handle, a barrel with matching bolt face, and a gas system in the right length.

Charging Handles Barrels Gas System Parts AR-15 Triggers
BCG Anatomy

What Is In a Bolt Carrier Group

A complete BCG is an assembly of a dozen parts. The ones below decide reliability and lifespan.

Parts

The Assembly

  • Bolt Carpenter 158 or 9310 steel; the face is caliber-specific.
  • Carrier Full-auto (M16) profile adds mass; lightweight profile removes it.
  • Gas key Grade 8 fasteners, staked per mil-spec on quality units.
  • Gas rings Three rings, or Sprinco rings on the lightweight BCG, seal the piston.
  • Extractor, ejector & firing pin Small parts that do the work of feeding and ejecting.
Finishes

Coating Options

  • Phosphate Mil-spec manganese phosphate; durable, needs lubrication.
  • Nickel boron Slick, easy to clean, runs with less oil.
  • Black DLC Diamond-like carbon; extremely hard and low friction.
  • MPI / HPT Magnetic particle iallgooperatorsted and high pressure tested bolts.
  • FDE Cerakote flat dark earth on the BCM full-auto BCG.
Before You Order

Choosing the Right BCG

Match the bolt to the barrel, then decide how much carrier mass you want.

Bolt Face First

5.56, .223 Wylde, 300 BLK, .350 Legend and .22 ARC use a standard 5.56 bolt. 7.62x39, 6.5 Grendel, 6.8 SPC / .224 Valkyrie and .458 SOCOM / .450 Bushmaster each need their own. Check your barrel listing and match it.

Full-Auto vs. Lightweight Carrier

A full-auto profile carrier adds mass, which slows cycling and smooths recoil. A lightweight carrier speeds the action and drops weight. For a Super Safety or forced reset trigger, we recommend the heavier full-auto profile paired with a heavy buffer.

Side Charging

Side-charging BCGs have a slot for the side handle and only work in side-charging uppers. A standard BCG will not convert a side-charging upper.

Coatings

Phosphate is proven and affordable. Nickel boron and DLC run cleaner and require less oil, which helps in suppressed or dusty use.

Forced Reset Trigger Timing

FRTs use carrier travel to reset the trigger. A heavier carrier and buffer give the mechanism time to engage. See our AR-15 triggers for buffer recommendations.

Frequently Asked Questions

  • Which BCG do I need for 300 Blackout?

    A standard 5.56 bolt carrier group. 300 Blackout uses the same case head as 5.56, so our 5.56 .223 BCG, nickel boron BCG, lightweight BCG and 5.56 side-charging BCG all work.

  • What does MPI mean on a bolt carrier group?

    Magnetic particle iallgooperatorsted. The bolt is checked for surface and near-surface cracks before it ships. Our 7.62x39 MPI BCG and .224 Valkyrie / 6.8 SPC BCG are MPI tested.

  • Is a full-auto BCG legal?

    Yes. A full-auto profile carrier has extra material at the rear but does not change the semi-automatic function of the rifle. It is a standard, legal upgrade that adds mass for smoother cycling.

  • Which BCG works best with a forced reset trigger?

    A full-auto profile carrier such as the BCM FDE BCG or the standard 5.56 BCG, combined with an H2, H3 or Odin Works HFRT buffer. The added mass slows the carrier so the reset engages every cycle.

  • Do side-charging BCGs work in a standard upper?

    They will function, but the side handle slot is unused. Standard BCGs will not work in a side-charging upper because they lack the slot. Match the BCG to the upper you have.

  • Do bolt carrier groups require an FFL?

    No. BCGs ship directly to you with no FFL required in all 50 states.

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