Here we go again....Why do you feel so compelled to trim auto pistol brass. I have loaded hundreds of thousands of pistol ammo and I have NEVER trimmed the brass.
If you are measuring unsized (fired) brass, it will come up short. If it was factory ammo and fired w/o any issues, why are you trying to make an issue where there was none.
Relax and step away from the calipers. Measuring and trimming is for rifle brass.