If you are going to buy extra magazines for your Glock, the best magazines are these Factory Glock magazines. These are the very same magazines that Glock ships out with their pistol. They are made to exacting standards and inspect, just like every other Glock part. There are plenty of other, cheaper Glock magazines out there, but several users report issues with them. Sticking with the factory magazines is the way to go. The OEM Factory Glock mags are built tough, with a hardened steel frame and a high-tech polymer over coating. The steel liner provides excellent support to these magazines while the polymer coating helps the mags retain their shape and absorb impact so that they drop free every time. Also, this polymer coating helps to protect against corrosion.
In order to ensure maximum reliability, Glock uses very strong springs with their magazines. Because of this use of strong springs, it may be difficult to load the magazine to full capacity the first several times. One method that may alleviate this issue to a degree would be to load the magazine with as many rounds as you can and let it sit at least overnight and then check to see if that last round goes in a little easier.
This magazine is compatible with all .40 caliber Glocks from Gen 1-Gen4
Buying extra magazine for your Glock is a wise investment. It will allow you to get much more out of your gun and less effort. For instance, if you use you’re your Glock for concealed carry, you could have a couple magazine dedicated to that purpose and have them only loaded with your defensive ammunition. And also, you could have a few more that are related for training and range use. That way you don’t have to worry about loading and unloading your carry ammo and potentially mistaking your carry ammo for range ammo or vice versa. You can further distinguish your magazines by having orange base plates on your training magazines.