Yes, they will stick-out a little bit. They probably have an extended base on them, sometimes called a "Plus" or "Plus two" base. It allows a bit more room in the mag body, enough to add 2 more rounds of 9mm, or one more round of .40 ammo. There have been two different versions made by Glock, and several non-Glock-factory copies. The older models can be seen in this photo, on the two guns to the left side:






I found this photo while searching the web (rehosted), and I believe it shows the newer extended bases:

Or it's a mag for a G17, and it will stick out hte bottom a little too. They make spacers so that the mag is the same shape as the grip where it sticks out, but heads up, they can pinch your hand on reloads.

Okay, thanks for the information. I really don't need a 17 round magazine and I'd prefer that it not stick out. I will start looking for the 15 round mags. Thanks again.

John