I was still having a feeding problem with my RPR .22Magnum rifle recently, and finally figured out what might be a fix after digging around on the Ruger site some. It seems to be a fairly common problem, and the recommended fix (assuming no other issues with the BX15 Magnum mags) is to remove the short throw clip on the bolt. Apparently this allows the bolt to be better aligned to strip the rounds from the mag. Since it's a simple task, I tried it out and the feeding problem went away!! Yay! As a side benefit, it also smoothed up the bolt travel somewhat.
I don't know if the issue effects the .22LR model.
