SureFire | Optimized Bolt Carrier Group

The SureFire SF‑OBC‑556 is an Optimized Bolt Carrier group for 5.56 mm / .223 AR‑pattern rifles, designed by Jim Sullivan. Long‑stroke carrier travel about 60% farther past the magazine than a standard BCG, plus a dual‑spring dwell weight that delays the carrier's direction change. Revised cam path delays bolt unlock for about 15% lower chamber pressure before opening, which cuts gas into the upper on suppressed guns. Neutrally balanced counterweight for lock‑up and less bolt bounce. DLC and S‑Line anti‑friction coatings. Kit includes the carrier, buffer spring, and long‑stroke H‑weight buffer. Alloy steel, 13.6 ounces. Mil‑Spec bolt, proof‑tested and magnetic‑particle inspected.