USPSA's Robin Taylor applies his experience with Glocks to the new "Gen 4" model. He says Glock's new variant offers many improvements of interest to Glock-shooting competitors worldwide. The Glock is already the most-popular gun used in Production Division in the United States and has a strong following in other divisions as well. This new "Gen" adds removable backstraps, a larger, reversible mag release, and much more. Download story.
EXCERPT: In essence, the Gen 4 is what Glock enthusiasts would call an "SF" 9mm ("SF" stands for "small frame") with the added ability to extend the grip. Going "SF" means the trigger reach has been shortened, and the curves at the back flattened slightly to make the pistol easier to get your hand around. This makes the mag release easier to reach for people with relatively short fingers (a common anti-Glock complaint).
To pad the "SF" Gen 4 out to the normal "Gen 3" profile, one pins a "backstrap" onto the grip. The medium "backstrap" itself is really a backstrap cover that has little structural integrity of its own. It's a thin bit of polymer, retained by two polymer hooks at the bottom and a slightly over-size, over-length trigger housing pin at the top. To make the pistol even longer, mount the "large" backstrap cover instead, and you have a gun somewhere between the standard 9mm frame and Glock's famously-beefy .45 (the Glock 21). While the gun isn't any wider, the length makes it feel as though it is. I have relatively long fingers (I can shoot a Glock 21 easily), so this option appealed to me a great deal.
None of the "backstraps" change the width of the pistol at all. Instead the grip angle changes slightly, and the trigger reach changes. None of the changes are night-and-day obvious from the outside, but they're very noticeable in the hand. Thanks to the rough, rounded surfaces, my measurements in the accompanying table aren't exact, but they give you an idea of how much change is involved.
Mod. 2: "SF" Style Trigger Housing
Gone are the days when one trigger housing worked in every Glock in the line. To achieve the smaller "SF" frame dimensions, something had to change inside. That thing was primarily the trigger housing, which is shorter, and has beveled edges. It will NOT work in the Gen 1-3 Glock 17s (I tried).
There are also small changes to the trigger bar, altering some of the geometry relative to the trigger return spring. That part DOES interchange with a Gen 1-3 pistol in a pinch, but I haven't heard back from Glock about potential long-term use. . .