Having shooting problems?
Is your gun stuttering or not re-cocking?
This is caused by excess drag on the internals of the gun, or seals leaking and not providing enough pressure to re-cock the bolt.
Clean, lubricate and replace internal orings.
Is your gun auto firing or going full auto?
A worn sear or rear bolt will make the gun 'rapid fire' like an automatic, but too fast to work properly. The gun may not stay cocked either. These are both caused by the rear bolt slipping off of the sear that is supposed to catch it and keep it back in the cocked position. If either your sear or rear bolt is worn, it is suggested to replace both at the same time. A worn sear will wear down a rear bolt faster than normal and vice versa. Replacing only 1 of them may result in having to replace the same part again a lot sooner.
The sear spring, sear pins or trigger pins could also be worn. This maybe causing the sear to not sit in the proper position.
Is your gun having erratic or low velocities?
A bent part in the bolt system can cause velocity changes. Check the Drive Spring, Guide Pin, Linkage Arm, Front Bolt, and Rear Bolt for damage, nicks, or parts that aren't straight or sitting flush with the body.