The new 2.0 sub compact like the old m&p9c can run a flat base 10 round mag if needed like in some states ! My wife has had a couple of those for her 9c but she uses the pinky extension 12 rounders in it with a 17 round mag as back up with an X grip on it . Today with the 15 rounder and 23rounder it makes for a wide variety or mags we have in the house as we also have a 4.25 core now my wife's fun and house gun and I have a 4" compact optic ready . That ones for me if I ever feel the 40 or 45 are no longer enjoyable to keep up my training with or if I need a dot optic on a daily carry .