My Guess is that you need to take a long look at your powder measure. If you polish the brass before resizing the decappeing pin will clear the flash hole. If the bullet lobe has been thermal cycled in a trunk several times the bullet lube could be a factor.

My guess is contaminated primers or a large variation in charge weight are the problem. I have found that with light loads a tight crimp is a good thing. -If the seated bullet is the right diameter and will rotate with finger pressure you need to check your expander. I find in 38 that some mil spec brass they seat hard but that some commercial brass having thinner walls can be somewhat loose. I chuck up the expander and 000 steel wool it to my specs!