The Glocks and XDs only hold 13 rounds too. This mag pretty much the exact same size as the Glock and XD mags too, minus the bumper on the floorplate.
And its pretty accurate too. This is an offhand group at 10 yards.



And I got my surefire X300 for it the other day. I plan on making a holster for it Monday. Im thinking OD green.




And the grip size is AMAZING compared to a G21. Its almost the same size as an M9.