The only cases that have caused me any problems have been the "Amerc" brass from some American Ammo I bought some time back. Some cases wouldn't fit into the shell holder, and the primer pockets are pretty loose after the initial firing. I picked up a few cases last time I went shooting that were marked Federal 07 on them, and the primer pockets were swaged real tight, and I wound up chunking them. Also watch out for the Winclean?? cases that have the small primers in them.