Yes, Bad Karma is absolutely correct. When the hammer contacts the rear of the cylinder to engage the pin, it is not moving the small additional distance that it would to hit the nipple. Correcting the upside down concave portion of the bolt (a very small bit) and or polishing the bolt can correct this. Read the above listed book. If you are not comfortable doing this send the off the Mike at Goon’s Guns.The bolt leg is not resetting on the cam. Stone the leg gently until it does. Kuhnhausens book shows the process.