I reloaded and shot through my first batch of 9mm brass with no problems. I knew some brass were close to needing trimmed prior to firing, so after firing them, I bought a Lee gauge and shellholder for my Lee trimmer. After cleaning and resizing, I went to trim, and found my trimmer would only fit into the mouth of about 1/2 of my cases. Not sure if the problem is originating with the brass or dies. Advice for troubleshooting?