If the loaded cartridges fit well in two other S&W .357's, then the cylinder becomes suspect. If they only get tight at the very end, then maybe your gun shot a lot of .38's and not much .357, so the ends of the cylinder may just need a serious cleaning. Have you tried putting a bore brush & rod on a drill and working it pretty hard in the cylinder, NOT the barrel? Does the gun shoot .38 Specials OK?

Also, is it only one charge hole that is too snug?

Lots more investigation to do. Until you get a good solution, I'd keep the loads on the light side.