Yeah I know, a real surprise when it comes to ProMag. I thought I'd take a chance on a 15-round ProMag HIP-A5 for my 4095TS and JCP. All four HP mags are GTG. The ProMag doesn't seat/lock in either the 4095 or JCP. I compared the ProMag to the HPs...looked at them a thousand different ways and had trouble finding any difference. I finally found the culprit, I think. OEM ProMag The channel on the inside of the mag is different. On the HP, there's space from the channel to the edge the mag release hole. The ProMag channel goes all the way to the edge which keeps the mag release button from locking the mag in place. I have no idea how to take apart the ProMag or if it can be fixed by removing that extra material...maybe with a Dremel. Anyone have an idea other than don't buy another ProMag...already figure that one out on my own already?