My latest acquisition as of today. Military & Police 4th Change. Serial number is 55XXXX. Figure it was manufactured sometime following WWI into the mid- twenties. I stopped in at my favorite local gun-shop yesterday. Just a little hole in the wall place. The owner actually runs an autobody shop and his gun business is a hobby. It is located off of his office area and only people who are longtime customers know about the place (I've been buying from him since 2003). Anyway, I stopped in, and he had four M&P 4th change revolvers for sale. I jumped on the 4"-barrel model and had it pulled until I could pay for it. A few hours later a guy came in and bought the other three. He asked about the 4" but he was too late. For once I was ahead of the of the crowd. Took one with my Colt OP. Both are from the same era and good representations of classic cop guns. Incidentally I paid $650 out the door. I suppose some might feel I overpaid,but considering today's market I'm happy. The bore is very clean as is the entire piece. In excellent mechanical shape as well.