Is that a gun you seen for sale that is advertised wrong? Or do you have the gun.It just looks like a model 27 to me with cheap grips.Or some one went to a lot of trouble to checker the rib on the barrel to match a model 27
It seems to me that the checkered rib is the only thing that would be "troublesome" about the conversion. Obviously started with a M27 -2 frame, could have been either a .45ACP cylinder fitted, or rechamber the M27 cylinder to .45 ACP.
A Model 26 (Model of 1950) barrel could have been fitted, that would account for the barrel marking, but then the rib would need to have been checkered, as I believe only M27 barrels got that. On the other hand, a M27 barrel could have been re-bored, and that would account for the checkering, but then the original barrel marking would have been removed and the barrel remarked. In either case then throw in a reblue.
I'm inclined to think a Model 26 barrel was used and checkered.
From what I see it's a 1950 .45 cal. barrel that's been checkered. As they ran the checkering from the rib up the ramp and across the flat of the ramp, then shortened the patridge sight blade. I would think that the cyl. lug on the left side would have to be re-worked also to prevent the acp cyl. from slappin' back and too on the yoke when the cylinder is open, as the 27-2 had longer recessed cylinders. IMO a nice handy .45...
Back in the '70s Model 25s were hard to find and was a cottage industry developed that specialized in converting Model 27s and 28 to .44 Special and .45 ACP. This sounds like a Model 1950 barrel and .45 ACP cylinder were fitted. If they did a good job, it could be really nice.