Quote Originally Posted by Artfull-Bodger View Post
Don't wish to contradict Tin but I have been fitting needle roller thrust bearings for a while to counteract spring torque, if you have a rotating piston it makes little difference although it does help, I have tested this back to back, but on a non rotating piston like a HW77 it makes a big difference to the lateral movement of the rifle.

I test the bearings by firing the rifle at a 1cm square grid at 10yds, I aim at a highlighted point and freeze in place after the shot , then measure the distance the crosshair has come of target, do this ten times to get an average reading, fit the bearings and run the test again, in every case the bearings reduced lateral movement to practically nil, you can actually feel the difference.

It's not contradicary, just another approach. As for testing, I just shoot and watch the crosshairs. I'm not saying rollers dont work, or rotating pistons. But roller bearings are susceptible to getting crud in them and a rotating piston with a slip washer works better than a rotating piston alone. And if people want to fit roller bearings at the rear then it can only help. 🙂