A while back I was having a heck of a time getting any consistency from my new Hornady Cam Lock case trimmer, and I complained about it here. It isn't easy to get repeatable results with the thing right out of the box, and I still had to replace all of my shell holders with Hornady's just to get the thing to work at all, but by golly, after trimming about 1000 cases, this last batch turned out with +/- .002" accuracy or better. Most were better, in fact.
Next time I'll get something electric, since I'm beginning to develop Reloader's Elbow from cranking this thing, but it's damned accurate with the right procedure and practice. Like everyting else made by Hornady that I've tried so far - excepting shell holders - this is a perfectly acceptable machine capable of exceptional results in the right hands. Happily, my hands are getting smarter.