I used a 22-250 case because the rim size is only a few thousands larger that the OD of the sleeve. I had to "work down" the remainder of the case though. I used a .125 (1/8") ball and let the ball set in the flash hole, which I put a small radius in to hold the ball, because the exposure of the ball was only about .015" above the rim of the 22-250 case. After cycling the action many times, I can see a small "print" where the ball is contacting with the bolt. This tells me that the ball is staying centered in the flash hole. Also my total increase in length was about .075". I added a modified washer BETWEEN the bolt handle and the bolt the same thickness to make up for the increase caused by the bearing/22-250 assembly to keep "all things equal".

There is pressure on the ball at all times, so I saw no need to glue the ball in place, once assembled, I believe it will stay there. Also it's "trapped" in the primer pocket.

Just another way of accomplishing the same goal ... I guess.