The SureFire OBC is designed to greatly increase the reliability of an M4/M16/AR variant during both unsuppressed and suppressed firing. The OBC comes as a package with the OBC bolt carrer group as well as buffer and buffer spring. This patented design makes numerous improvements to the standard Mil-Spec full-auto bolt carrier group starting with delayed unlocking of the bolt during the firing sequence. This delayed unlocking is a result of a lengthened cam pin slot and our neutrally balanced counterweight. This delay allows expanding gases more time to exit the bore, lowering chamber pressure by 15%, which not only reduces wear and tear on parts, but also reduces back-pressure gases exiting the ejection port.
Features
	
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