Barrel looks longer than 4" to me as well. You must measure from the muzzle to the front of the cylinder. Often people measure from the muzzle to the point where the barrel joins the frame, hence the short measurement.

Family stories often change as they are handed down from generation to generation. I wonder if he got it from a policeman. Or from a police sale. I believe I have heard that back in the day police departments would sell off guns they had confiscated from miscreants or found at crime scenes. Money was tight, especially in the 1930s. Guns were not vilified to the extent they are today so I doubt anyone back then would object to that practice. In fact, there would probably be a lot more of an outcry if such guns were melted down. Different times.

__________________
You're shy a few manners.