I've always heard it's a Kaboom around the corner loading 180 gr bullets in .40 S&W. With the high pressure the .40 S&W operates at any setback or decrease in OAL can cause a severe pressure increase and apparently the 180 gr bullets cause more problems. Thus, only load 155 gr bullets and feel that's more than I need. I save the 180 and 200 gr bullets for 10mm.