I'm loading for my AR15. How fussy do I have to be about trimming brass? I've got a bunch of .223/5.56mm cases and want to reload them, but I'm not sure exactly what I need to do in terms of trimming. I know max case length for .223 is 1.760 inches and that this length should not be exceeded, but I'm not sure as to what length I SHOULD trim them. This is what I'm doing right now, please let me know if it's not correct. Because I want a consistent crimp I'm trimming everything in batches to the same length. For instance, when measuring my cases before trimming, some come in at or around 1.752 inches, some at or around 1.749 inches, etc. So I've been trimming a batch of 20 of the at or around 1.752 inches all down to 1.751 inches and the at or around 1.749 inches all down to 1.748 inches. Also, sometimes (after trimming) the digital caliper numbers jump a bit when measuring the case, say from 1.7485 inches to 1.749 inches (or even 1.750) and then to 1.748 inches. What do I call that case length? How precise should I expect my measurment to be? Is this how I should be doing it? Or am I doing something wrong? How fussy do I have to be about trimming brass? Would I be better off just setting my calipers to 1.760 inches and just make sure everything fits and then be good to go? Also, what is the minimum case length for .223/5.56mm?