I have been looking for a 3 or 4 inch barrel for CCW - I'd prefer a 3 but would settle on a 4. I like more "vintage revolvers"
The M-10, or M&P's with 4" barrel are still out there and should be easy to locate. The M-10 was also produced with a 3" barrel. It may be easier and less costly to buy a factory gun than have one converted.
Best of luck what ever you do.