I got serious about good crimping when several years ago I was loading for 40S&W. I was getting overload signs, stovepipes, and blown primers. I then investigated and found that the feed ramp was little steep and caused the bullet to be pushed back slightly when chambering with the RCBS seating die even with a good crimp. After some more investigating, I found 40S&W and 357sigis one round that can be dangerous high pressure if the bullet slides back. I found it fruitful for future shootin to put a good crimp. Now, I can cycle my rounds thru my gun and have no issues with them moving back at all. Lots of 40's have tore semis apart due to the bullet moving back.