M4 (T.Marui) CNC Steel Bolt B

This steel Bolt B (part No.133), which is made by precision CNC process, and steel screw (part No.134) set is made for M4 (T.Marui) GBB.  This steel Bolt B is 23g heavier than the original part.  Therefore, this 1.79 times heavier in weight increases the recoil shock moderately but it does not slowing down the recoil speed significantly, and the smooth finishing minimises friction around the buffer tube.