Machined to the same exacting tolerances as JP's bolt carriers, this third generation 9mm bolt assembly eliminates the need for a central mass (slug) to readily function with their 9mm JP Silent Captured Spring without compromising bolt weight and reliability. In fact, when combined with our JPSCS-9MM, you have the heaviest, most reliable 9mm operating system that dramatically reduces bolt bounce while improving accuracy. This bolt assembly is heavier than the Rock River Arms 9mm bolt with its central mass removed. When used in conjunction with the Silent Captured Spring, the complete JP 9mm operating system is slightly heavier than the complete RRA bolt and buffer, some of the bo Mfg: J P Enterprises