sized brass won't chamber

[Catfish]

Welcome aboard Niel.
My first guess is that you are not full lenth resizeing your cases. When you FL size brass you push a wave of brass down the case in frount of the die. If you stop befor you bottom out it will leave a ring on your case that is larger than the case dia. If your dies are not set to where the contact the shell holder, but very close your ammo will seem to fit well right up to the point you try to close the blot handle but it just won`t want to close. Try running the ram on your press to the top and then screw your die down till it`s touching the shell holder. My guess is that will fix your problem.