AR Sponsor
Posted: 3/8/2009 8:19:07 PM EDT
|
I have been trying to get my new upper to work and have been having a 10-20% FTF issue with all ammo tried. I have an RRA 2 stage trigger group in it.
I had previously polished all moving parts to a mirror finish, and had polished the strike face of the hammer. After disassembly, I noticed on the rear of the bolt directly below the firing pin a dent that was not there when new....the hammer was not hitting the firing pin full on and was actually hitting the bolt before striking the head of the firing pin. I took a flat needle fie and filed a slight bevel from the bottom of the FP hole (remove FP first) to the rounded camming surface on the bottom of the bolt. The bevel went from nothing (at the FP hole) to approx. .025" deep at the bottom of the bolt. I then blended the bevel into the rounded surface on the bottom and polished everything back to a mirror finish. The gun was 100% on the last 150 shots I fired. Check yours, the hammer should be hitting the FP full on, not at an angle, or partially. Take a black marker to the hammer and rear of the bolt and see where the contact is. The real problem is the bolt is about ..030 too long back there and the hammer doesn't hit the rear of the bolt squarely. HTH someone, they make you cuss a lot when they are jamming and smile a lot when they work! Brad |
AR Sponsor