I find it interesting that my m&p .45 "compact" is virtually the same size as my m&p .40 mid size. I can carry either & if I stick my 9mm barrel in it, I get 17+1 capacity. While it's not exactly what you're asking, I just find out interesting I can double my capacity by carrying a different caliber, yet same sized pistol.

S&W M&P 40 Mid (EDC) - S&W Shields (his/hers) - S&W M&P .45C - S&W 4513TSW .45 (1st Gen, retired to nightstand)
CMMG AR15 w/ACOG
Anderson AR15 pistol w/Aimpoint H1
08/04/2013 CHL class taken - plastic rec'd 08/26! Renewed 2018