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SF-OBC-556 Optimized Bolt Carrier Group

Optimized Bolt Carrier Group for M4/M16/AR-Variant Rifles & Carbines

  • SureFire's next-generation bolt carrier group, optimized for 5.56 mm/.223 caliber rifles and carbines
  • Long-stroke design increases reliability when firing suppressed or unsuppressed
  • Includes optimized bolt carrier, buffer spring and long-stroke, H-weight buffer

Double Down on Reliability. Invented by Jim Sullivan, one of the original designers of the M16, the SureFire Optimized Bolt Carrier (OBC) doubles the reliability of any M4/M16/AR variant weapon system during suppressed and suppressed firing. Its patented design allows more time for reliable feeding of ammunition from the magazine and nearly eliminating bolt-over-base malfunctions. The OBC also delays unlocking of the bolt during the firing sequence, which allows expanding gases more time to exit the bore, in turn reducing back-pressure gases exiting the upper receiver group. Additionally, the neutrally balanced counterweight improves carrier and barrel extension lock-up, nearly eliminating bolt bounce. The OBC reduces felt recoil for better target tracking and greater weapon control when firing. Coated with an advanced anti-friction coating, the OBC resists friction during use and makes cleaning easy.



  • Designed by firearms industry legend and M16 designer Jim Sullivan
  • Long-stroke design delivers 60% more travel beyond the magazine, increasing magazine feed time and reducing the chance of bolt-over-base malfunctions
  • Dual-spring dwell weight significantly delays bolt carrier direction-change for increased reliability
  • Improved cam path delays bolt unlocking for a 15% decrease in chamber pressure before unlocking
  • Self-lubricating, Diamond-Like Carbon (DLC) and S-Line coatings reduce friction for consistent, dependable operation in the most adverse conditions
  • Mil-Spec bolt proof-tested and magnetic particle-inspected to meet the highest standards



Key Attributes

5.56 mm
Steel Alloy
DLC and S-Line Anti-Friction Coatings
13.6 oz (385 g)

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