You bought a 2 1/2" M-19-3 that has been re-barreled. Notice that the top of the frame straight. This feature only appears on 2 1/2" guns. It is done so that the sight ramp on the short barrel neatly meets the top of the frame. M-19's with longer barrels have a step there. Look for some other pictures of M-19's on the forum and you'll see what I mean. Of course, the only way to know is to letter it. There's always a possibility that someone ordered a round butt frame with a 4" barrel and S&W did it. However, I think the chance of that being the case is very small.What in the world did I do?
This one is pinned and appears to be recessed, which would be correct for a 19-3. This makes me think the barrel was changed later in life. However, it does appear to be a LEO gun, so it could have been a special order.Near the end of production of M19s, a bunch of them did come out that way.