Ok so after a few reloads on my Lapua .260 brass I had to switch primers and only had a box of Winchesters around. I had never tried them before. So I seated them and most were loose, I thought that perhaps my brass had seen it's end on it's third load? Was I blowing my brass out? So after firing that brass loaded with the Win primers I tried the cases out again with some Federal and all was good. Primers fit nice and tight. It's possible that Win primers are super soft?