At the PD I worked at, all the AR GI aluminum mags got dumped many years ago and switched to P-mags. I got many used GI mags for free and installed new springs, followers and floor plates. I also have gen 1 through 3 AR P mags. All work fine. I have tried the p mags in Glocks I have and they work without problems. I also just use them at the range. Glock mags are cheap and work, heck the state agency I worked for gave them to officers. As a range guy, at one time, we changed out the Glock mag springs and inspected the mags of the officers at about every 5 years. After a couple of cycles, it was just issue new mags. Cheaper than inspecting and rebuilding old. I personally don't know anyone working a cop job using p mags in Glocks. I bet there are, I just don't know any.