Surefire Optimized Bolt Carrier System
Invented by Jim Sullivan, one of the original designers of the M16, the SureFire Optimized Bolt Carrier (OBC) is designed to improve the functionality of an M4/M16/AR variant weapon system during both unsuppressed and suppressed firing. This patented design makes numerous improvements to the standard Mil-Spec full-auto bolt carrier group which allows more time for reliable feeding of ammunition from the magazine, 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 also reduces felt recoil, allowing for better tracking of sights and more control of the weapon when firing. Coated with an advanced anti-friction coating, the OBC resists friction during use and makes cleaning easy. For the ultimate in reliability, choose the SureFire OBC.
- Neutrally balanced counterweight automatically reduces cyclic rate, negating the need for switch or setting adjustments.
- Improved cam path delays unlocking, allowing the chamber pressure to drop another 15% which permits more gasses to exit the bore
- Nearly eliminates bolt bounce
- Long stroke design improves reliability, allowing ammunition more time to feed properly
- Utilizes Mil-Spec bolt and components
- Anti-friction coating resists corrosion and makes cleaning easy
- SF-OBC-556 comes standard with Optimized Bolt Carrier, Long-Stroke Buffer, and Improved Buffer Spring