Keep in mind that there are 2 types of factory mags: drop-free (or full metal lined) and non-drop-free (or non-full-metal-lined). Drop free's will fall out of the mag well without any help even if they are fully loaded. Non-drop-free's swell up a little, and will stick inside the mag well if they're still full. Drop-frees are generally considered superior, but it's really just a matter of taste. The mags go for 65-85 dollars for the non-drop-frees, and about 10 bucks more for the drop-frees. By the way, the Glockm 19 is a great all purpose gun.