I have 2x40 and 1x30 Pmag while doing 3gun south of the border. Unless there is some specific reason on the stage for running the shorter 30, I start with the 40 and then have a 30 or 40 on my belt as second/backup mag.
Also keep in mind that you lose reliability if you run Pmags at 100% capacity, or try to insert them on a closed bolt. So I'll basically always down-load the Pmags by 1 or 2.
I was at a match last year in North Carolina that limited mag capacity for both rifle and pistol...40 round rifle mags put you in open...That was new for me but several of my squad mates said they were starting to see that at some club level and at least one regional match so something else to be aware of.




















































