Ric, I assume FS= full size, but aren't they double stack mags, vs the single stack for the Shield?
I originally bought the Shield in .40, because that's what I could get. Now the same LGS has the 9 Shield available.
Before I invest more in .40 mags and .40 ammo,, I may be better off with a 9 shield.
I did get the NDZ Performance mag bases with the pinky extension and like the feel with the short mag and the base in the Shield. Per IDPA rules, 8+ gets you 2 extra mags or 25 to 31 rounds, 6 or 7 gets you 3 mags or 25 rounds (6 rounders) or 29 rounds (7 rounders)
If I switch to the 9 shield, use the short 7 round magazines with the pinky extension (which feels the best to me) I shoot a string with 29 rounds. Or stick with my .40 and have slightly higher ammo expense and shoot the strings with 25 rounds.
I'm not necessarily concerned with 25 vs 29, but I guess I need to shoot a match or three and decide on my course of action.
By the way, I carry the Shield 40 every day.
Thanks for the input.