Yes, if you rack the slide(cock the striker) you can flip the safety freely, so you CAN put in your mag & lock the slide shut, in that order. I don't see how you can turn the safety on an open slide if it locks the slide shut. If no one has tried this by Monday, I work in a LGS in my area & will try for you. As I did own an Sr9 but no longer do as my g17 has become my house gun.