As an owner of a 639 since the early 90's, I was handling a used model 639 which had a tag, "magazine:9+1" I asked the salesman if it were a mistake, he said no. I told him I've never seen a 639 mag that held more than 8. He opened a box of 9mm reloads and proceeded to push 9 rounds into it and slid it into the 639 and smiled. Question 639 owners, what mag is this and where can I get a few? It is a S&W mag, but it surely must be from another model that happens to function in the place of normal 8-round 639 mags.