I finally bought the combination of a ATI stock and the elusive 15 round magazine for my highpoint 9 mm carbine. I came in today and after a less than simple instalation of the stock, it came to my dissapointment that the plastic shroud for the mag was too long for the mag to catch on the release and without it, the mag simply fits too loosly in the grip. Evidentally, the 15 round magazine only fits the ATI stock after the shroud has had about 1 1/2 cm cut from its top and smoothed out with a rotary tool. I just wanted to give a heads up to anyone looking to upgrade their carbine.
