On the matter of changing the colours/coating of handgun magazines as used in Production division:
The current IPSC competition rules are mum on the specifics of colour change of magazines in PD. Appendix D4 item 16.1 addresses the change of colour and/or finish of the handgun, not its ancillary equipment. Furthermore, D4 item 17.1 indicates aftermarket magazine are permitted, not specifying colour and/or finish.
From above it would be reasonable to accept that a change in the colour and/or finish of the magazines would be permissible. To substantiate this view, a mail from Vince Pinto (Director; IPSC Handgun Rules) serves to confirm the matter, i.e. it is permitted to change the finish/colour of the magazines, and that 16.1 do not apply to the magazines.
South African Institute of Range Officers & Instructors