I had one of my Gen 2, two pin 17s lock open prematurely a couple of times today. The first time I guessed that it might have been bad thumb position, but I started paying closer attention to my grip and it locked open a secont time on the next shot string. The RO was also watching to see if my thumb was bumping the lever and he confirmed that it wasn't a grip/thumb position issue. When I got the gun home I compared it to one of my Gen Three 17s and found that due to the extra pin in the 3 pin models the spring is under a good deal more tension in the 3 pin models than in the 2 pin models. This particular gun has a Glock extended lever on it and I'm thinking that the combination of the extended lever (a bit more mass out on the end of the lever which might make it move around more during recoil) and less tension on the spring due to the lack of the third pin is what was causing the problem. Does anyone market a slightly more robust spring for the G17 slide stop?