Pellet Sizes and Fit recommendation

I have been testing a few pellets and have a question. I have two pellets that are about identical in groups. They are the JSB 8.44grns, .452 and H&N FTT 8.64 grns, 4.50. The difference is the way they load. The JSB pushes in the chamber easily while the H&N takes a bit of effort as they are tighter. Most of the time the H&N's can turn a little sideways. I was concerned as my thought was this could be bad for the seal or start to wear or tear it. I'm not sure as this is my first serious pellet gun. Thanks in advance fo the advice.