You know I don't remember. I remove the magazine disconnect on all my guns, but I can't recall if I pulled the firing pin safety on any of them during this. I will say that in the case of the 639 slide on the 6906 frame, I couldn't even get the slide on the rails, so it was moot. Also, the 39-2 slide on the 3913 frame, same thing: didn't fit on the fame at all.