Hi Bob in MO--
When I started using the Lee cutter, lock stud and case length gauge to trim I had no end of trouble.
It just wouldn't stay at the correct length for long.
When it was screwed all the way in I got too much trim and when I left it partially screwed in it changed length on me as I went along.
I believe it was one of the guys here at one point mentioned using blue loc-tite to secure the case length gauge in the cutter.
Just put some loc-tite on the case gauge threads, trim a couple cases, and as soon you get it set to trim at your preferred length, set it aside and let it cure for a few days. The loc-tite won't set up right away so you have a bit of time to get it adjusted.
Once I did that I haven't had to adjust since, and no problems with consistency. For .223 I get 1.750" every time.
(well, from 1.7495" - 1.7505" anyway.)
Of course, I'm only trimming .223 cases so I don't mind having it stuck together. The loc-tite will break free if I need it to.
I have the zip trim also...boy, that thing is...cute, shall we say.
Reminds me of the junk toys I used to get at christmas in the '70s.
The internal flat wound spring comes off it's mooring every few hundred cases and I have to un-mount it, take it apart and re-fix the thing. One of these days I'm gonna epoxy that thing in place.
I still think it's a clever little device, though. Works pretty well when it works.
I use it every now and then if it's late and the power drill would be too noisy.
All that said, I am looking to get a Forster trimmer kit myself but for now, the cheapo set-up works ok for me.
--edited for spelling.