Thanks for the info...
I just got my CZ mag...and have been working to make it 170mm USPSA legal...
think I got it figured out..
I tried a standard length extra power wolffe spring..without a tweaking the follower I got 28 easily in the mag..that cycled through my SP01..I'd like to get a slightly longer spring into it, possibly shorten the follower..
I have to shorten the rear end of the mag slightly which should not be a big deal..and if I can get to run 27-29 rounds..this will be great...

Here it is..I shortened the back end..so it fits the gauge..using a wolffe spring and the factory follower..I can get 28 rounds in that cycle through my SP01..
I need to get hold of some followers and long magsprings so I can get the right combo together...
and then I just need to build an USPSA/IPSC open gun..