I've read quite a few threads about the EAA Witness on this board, so I think my fix might be able to help someone here. As a lot of people have found out, the 10mm and .40 S&W factory mags for the large frame Witness pistols are nothing short of awful.
My first solution worked, but it was a little more complicated than I liked. (It involved TZ-75 followers and modifying a Wolff spring.) It's taken me a while and several experiments, but I finally have a second, very simple solution that works even better.
If you replace the internals of a 10mm EAA Witness magazine with the follower and spring from a .45 ACP Mec-Gar Witness magazine or .38 Super Mec-Gar Witness magazine , then you can reliably feed .40 S&W or 10mm!
Mec-Gar uses a properly designed follower and a higher quality spring. That's all it takes to get these pistols working. The magazine body itself did not have to be modified.
Mine will even cycle 10mm, 175 grain Winchester Silvertips.
Magazine capacity was reduced in my pistol from 15 rounds to 14 rounds, however, now the Witness feeds without jamming.
It's a good idea to install an extra power firing pin spring in these pistols along with a more stout Wolff mainspring. Replacing the hammer spring also helps. I went from a 16 lbs to an 18 lbs for more reliable ignition.
Solution is also posted on the Witness board at CZ Forum:
http://www.czforumsite.info/index.php?topic=34651.0