Yeah I kinda wondered. If the fit is based on 3 things, bullet diameter, sabot thickness and bore diameter then as long as the first two remain the same it's up to the third. I've tried them in my Extreme which I know is .503 (doublechecked since I thought it was .502) and couldn't get any .40 bullet to shoot well. Your White is a .504 so I wouldn't think it would shoot. I just measured one and compressed as tight as I could get it I got .501 with a 40 cal shockwave (same diameter bullet).