I purchased a Gen4 26 about 6 months ago. When I got the pistol, I installed an extended slide stop lever. I noticed about every other magazine, the pistol wouldnt lock back after the last round. The more I shot it, it stopped locking back at all after the last round. I tried different 26 mags, 19 mags, and 17 mags, all Glock OEM. I also run WWB FMJ, some UMC FMJ, and some +P+ duty ammo that my Dad has without any change. My dad was the armorer at his agency before he retired, and has a lot of extra parts. I swapped the extended release lever for another one, with the same results. After trying 3 new extended release levers with no improvement, I installed a factory slide stop lever. The pistol now seems to reliably lock back. I run a couple of full magazines through it, and a couple with just one or two rounds in them. Has anyone else run into this problem with any of their pistols? I want to use the extended slide stop lever, but I also want the slide to lock back on an empty mag as it should. Ive read that there is a newer RSA for the 26, but mine has no numbers on it. Any thoughts?