I got a new 15 round mag from CZ-USA, Neither of my uplula's will let me push the 15th round in, same as the newer mag.
Comparisons:
old spring diameter: .0490 new spring diameter: .0520
" " coils 12 " " coils 12
" mag body: witness holes: 3 - sides " mag body: witness holes: 15 - spine
" locking plate: no tab on front " locking plate: tab on front
" mag body: no cut out, front bottom " mag body: cut out, front
The cut out on the front of the newest style (my term) mag is a rectangle for the tab in the locking plate to fit into.
The old style refers to the 15 rnd mags currently available from CZ-USA.
The new style are available at CZ-UB for approximately $32 US, but I tried to order some via their website and it wouldn't go through. But I tried.
Followers and base plates appear identical.
CZ's website does mention a stronger mag spring for the P07.