I reload 45/454 but mostly 10mm. I have trimmed 45LC cases once. It was when I reloaded some brass that came from a batch of cheap loaded ammo that I bought. After a couple of firings and resizings case length difference could be measured in 1/100". I have since scrapped that batch and now exclusively use Starline brass. Now I have one batch of Starline cases that's been fired twice and one brand new batch. The fired brass measure between .9825" and .9850". The new brass measures .9850 - .9880. I sampled about 5% of batches. I don't know how accurate my cheap digital caliper is and I'm also not sure that I'd be able be any more accurate with my trimming lathe. Any 5 cents welcome.