Jhp147,
I used to work for a gun shop at the time.
They still do round-butting and other custom work.
Round-butting costs about $40, and if it is a blued gun you need to have it reblued.
So, I first beadblasted the gun (which would cost a customer another $20) and then sent it thru bluing (which would cost you about $50).
I found this used police-trade-in 4" HB M10 in the Gunlist, or was it Shotgun News.
Anyway, they are out there if you look around.
I could've bought a replacement 3" barrel from brownells, but I didn't want to spend any more on parts.
Since the labor was free (I was doing all the work) I didn't mind finding another option.
So, I recut and crowned the barrel (customer cost $40).
That would be serviceable enough, but I didn't like that the barrel said "th & Wesson" on one side, and ".38 S&W Speci" on the other.
That's why I decided to slabside the barrel (which would probably be a $100 for a customer).
I think that a better option for most would be to buy a 3-4" M10 or M13, go with the roundbutting, and maybe trade-in the cost of the 4" barrel on a 3".
Then, beadblast and reblue.
-Kframe