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.
- 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