SureFire
OBC AR-15 Optimized Bolt Carrier Group
The SureFire OBC is a drop-in system that doubles the reliability of M4, M16 and AR-variant rifles. Its patented long-stroke design virtually eliminates bolt-over-base malfunctions. A new buffer and spring designed specifically for use with the OBC is also included.
The SureFire OBC eliminates bolt-over-base malfunctions by pausing the BCG at the open position. The OBC's long-stroke design incorporates a shortened gas carrier key in conjunction with a shorter buffer. This allows for a 60% increase in stroke length, which translates into two significant improvements: 1) it results in more clearance past the magazine, giving it more time to present the next cartridge for proper feeding, and 2) it increases momentum, reliably feeding rounds in adverse conditions. Other innovative and purpose-driven features include a lengthened cam pin slot, which keeps the bolt locked longer during the "unlocking" phase. This allows gases more time to exit the bore, lowering chamber pressure by 15%. This not only reduces incessant wear on components but also subdues back pressure and gases exiting the ejection port.
Additionally, the OBC incorporates a spring-loaded neutrally balanced counterweight that works three distinct times in the cycle of operation: First, the counterweight delays unlocking as the bolt begins its initial movement during the unlocking phase. Then, at the most rearward point of travel, the counterweight keeps the entire OBC in place, much like a dead-blow hammer, for additional time (again allowing more time for reliable feeding of ammunition from the magazine). And finally, the counterweight improves carrier and barrel extension lock-up in the locking phase, eliminating bolt bounce.
What’s Included
1x SureFire OBC Bolt Carrier Group
1x SureFire OBC Buffer
1x SureFire OBC Buffer Spring
Specifications
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