I remember in a Glock armorer's class where one of the fellows reported he was experiencing some repeated functioning issues when using a tac light on his G23. He was told to try different weight ammunition and see how it worked ...
I was speaking to a couple of fellows connected to another agency which had adopted G22's within the last few years. Their folks have been experiencing functioning issues when tac lights are installed on the guns. They were sent some new magazine springs and told to use them ...
Now, while the G22's locking block was redesigned in 2002 (the parts list I have at hand lists the locking block revision as being mid-2002), the same list shows only one locking block for the G23. I haven't received a newer list yet, though.
Granted, the pistol maker can't control the shooter & ammunition-related influences once the gun leaves the factory ... grip technique, maintenance (cleaning & lubrication practices, replacement of recoil & mag springs, etc), ammunition being used and the environmental conditions in which the guns are used.
Glock has been revising their .40 followers, too. When asked, folks from Glock often comment that this is to try and address functioning issues seemingly being reported by their LE customers when various .40 S&W loads are being used (bullet design & weight, power levels, etc.). Now, let's consider adding the use of tac lights to the mix.
Bottom line? A combination of gun, ammunition, maintenance practices, environmental circumstances and additional equipment (light) attached to the gun might consistently work well in one shooter's hands, but maybe not in another shooter's hands ...
When the issues was first reported by a federal agency using G22's, Glock determined it was caused by the expected frame flexion being affected by attaching a light to the frame. The 11-coil mag spring was created to replace the existing 10-coil mag spring in that model .40 pistol. The heavier spring was better able to provide the upward lift necessary to keep up with the increased slide velocities being encountered (feeding 'timing') when the frame wasn't able to flex to the anticipated degree. That's what we were told in an armorer's class, anyway.
Later on a different locking block was designed for the G22 (and related models using the same frame), FWIW.
If I knew someone who was going to use a tac light on a plastic framed pistol, I'd strongly recommend that they test-fire the combination of gun, ammunition and affixed light before deciding to use it for dedicated defensive purpose.
If a functioning issue arose I'd try and help them determine whether it could be addressed and resolved with the use of a different brand/bullet weight of defensive ammunition or by an adjustment to their shooting grip technique.
If there was an actual problem with the gun I'd either attempt to correct it with new parts, bringing it within normal spec as recommended, or have it returned to Glock for a more detailed examination if it seemed as though it required more than a simple repair.
Just my thoughts ...
