For the home guy not wanting to spend a lot to start. 1. Shim front of gas cylinder with a sliver of soda can aluminum, rubber mallet to start cylinder on. Then use the screw lock to push it on. Do not over tighten and have to back the lock up to install cylinder plug. 2. NM 4.5 lbs trigger job. Instructions can be found on line. If you have rare trigger parts replace them with imports and do the trigger job on the cheap parts. These two things can normally reduce group size by one third with good ammo. The rest is expensive.