Production division mandates starting with 10 rounds in the mag, so it takes a minimum of 4 mags to shoot the 32 round max per stage. One or 2 spares is good, in case you drop one or want to reload before slide lock or have a malfunction.
If your mags hold more than 10 (15 or 17 or whatever) then you can start shooting in Limited and load the mags up, so it does not take as many mags.
ETA: You said IPSC, I assume USPSA here in the USA. IPSC is 15 rounds max for Production.
Last edited by lmccrock; November 23, 2010 at 07:43 AM.
Reason: IPSC vs USPSA