I was recently gifted some 9mm Luger range brass by one the member of this site and after starting the full prepping on it, I started noticing that some of it just didn't look quite right. So I pulled out the calipers and started measuring. The Hornady Manual says the case length should be a Max. of .754 and the trim to length .744. None of these ran .744 or better. Most (so far) are running between .740 and .742 but there are quite a few that are running from .733 to .739. I have never reloaded the 9mm before and I am befuddled. While would anyone trim the cases that short and will the .740 to .744 be alright to load for my S&W Shield plus. The thing that bothers me is that the 9mm like most semi's headspace on the mouth and not the rim or shoulder. What say you 9mm experienced reloaders? Thanks for your time, james