Quote from earlier in thread:
One detail note: A32 has blue rings on the barrel as platoon and vehicle number identifiers but the decals supplied in the kit are actually black. So, I used a tip I saw in AFV Modeller magazine: I first painted the evacuator blue and then taped off the rings with Tamiya tape cut to the same width as the decals. I sprayed the area blue again to seal the edges of the tape and prevent the lighter color leaking underneath. Once that was dry, I sprayed the entire barrel using the various sand colors and peeled off the tape before that last layer was completely dry. Result is blue rings with little or no touch-up needed.

Here.

Cheers Rob.