I shot a competition yesterday, and picked up what brass I could. I ended up with 62 casings that were not my own. How do I know this? Because I color the head of my cases with a red marker. I know they are mine, and know what they are. This evening I went down and measured the length of those 62 cases, just to confirm what I already know. The shortest case was .821", and the longest case was .840". That is a difference of .019". I apply a light crimp to my loads and want every crimp to be the same. In fact, I want every round to be exactly the same. If I do not have consistant loads how can I expect to get consistant hits? Does not matter if I am shooting competition or just plinking. I want to hit what I am aiming at, time after time. Let's just say my own brass is .850" long. That is what a 40 caliber should be. If I throw those 62 cases in with mine what happens to my crimp? And, how consistant are my loads? After all, I now have at least one case that is .029" (that's TWENTY NINE THOUSANDS) shorter than my longest case. You know, that is equal to the gap on some spark plugs? I have been trimming my 40 caliber brass to .840" for years (I trim one time only). I do this because it is almost impossible to find once fired brass that is any longer. Factory ammo is notorious for having short, inconsistant case length. Is it necessary to trim handgun brass? You be the judge.