Nframe,I found and bought a 10 round at palmetto state armory. It was $27. I was hoping to find the 12 round.
Nframe,
Take your 10 round mags apart, there is a small aluminum spacer at the base of the spring. Remove it and you will have a 12 rounder. The mags are the same except for that spacer.
i bought 6-17 rd mags from 44 mag.com -factory mags too, ive used all 6 and they work perfect