It's been a long time (close to 30 years) since I have been in the east end of downtown Dallas, but I do remember once going into a sort-of pawn and gun shop place not too far from the Dallas police station. I seem to remember they sold a lot of cop stuff there also, and I think it was on Elm.

I'll go with Dallas PD as the most likely source.

Interesting to think it could have been on some downtown Dallas cop's hip when the JFK assassination occurred. I was in Dallas that day, but on the far east end of downtown. I didn't even know that JFK was in town until after the shooting.
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"If your revolver hasn't got a cylinder endshake issue, they probably used standard speed ammo, with wadcutters for practice and maybe, for qualification."

No endshake at all with the cylinder. The barrel-cylinder gap is very thin, can barely see a sliver of light through it, and the cylinder locks up tight on each chamber without any wiggle. Timing is perfect.

If I were still bluing guns (I haven't done that for about 10 years), this is one I would definitely blue. I'm leaving it as-is, I am not inclined to throw any money toward getting it refinished as it won't make it shoot any better.