I've been reloading .40 for years with 175 gr lead and recently switched to 180gr Missouri bullets lead. I use the same recipe and they function fine- the only change in my setup was I had to adjust the seating die just a hair to get same oal. I just randomly picked up a .40 case gauge and guess what, the new loads won't go all the way in but they fit in chamber and function perfectly. I had some of the leftover 185's and the fit the gauge perfectly. It appears there is a small bulge towards the bottom of the new loads. An clues on what's happening and how to fix? I use a Dillon 550. Thank you