I've had this Mark II for years and loved to shoot until, I started down the 22/45 Lite road. Periodically I shoot and then clean all of my firearms. Since I have been shooting my modified and smoothed 22/45's, the Mark II felt really rough while pulling the bolt back. Since I had it torn down I started to see what may have been contributing to this roughness and higher force to retract the bolt. When I looked at the top of the bolt I noticed that there were heavy machining marks on top of the bolt where the return spring stirrup rode. A few stokes with a file and stoning with 400 then 600 grit stones, I pulled out the Dremel and polished those two narrow surfaces. On the bottom of the bolt, there is a rub surface that pushes the hammer into the cocked position. This rub surface also had the same heavy machining marks as the top of the bolt. Again with a few strokes of a file and then 400 and 600 gritstone S it was ready for polish. After cleaning up the machining marks on the top and bottom of the bolt, I was amazed at how much easier it was to cycle the bolt. I could feel the difference while shooting and this aided increasing my fondness for this Mark II. I don't know if Ruger has improved their machining/finishing operations on the 22/45's or, is the stainless steel just more labor intensive than blued components. Now I have 4 Mark II/22-45 that are all easy to cycle manually or firing with less vibration. Note: minimal metal was removed, only 0.001"-0.003" to make a world of difference. Regards Neil S.