There was more then one gunsmith converting Pythons to .41 Magnum.
One I saw was an extraordinarily crude conversion with barrel stampings that looked like someone's kid had done them with a chisel.
One barrel mark was a laughably crude Serpentine Colt logo.
It looked like the "machine work" to make the conversion had been done with a dull file.
Latest info is that Colt got a request from a big distributor asking for something special to offer, and they wanted a Python in .41 Magnum.
Colt made up 2 or 3 prototypes, then had second thoughts and recalled the one they sent to the distributor.
Last I heard, all 3 were in the Colt museum and were sold in the big Colt auctions a few years ago.
Other then that, Colt made up one Python in .256, fired one shot and it locked up.
They also apparently made up a couple in .22 LR, and even had them on the cover of a Colt catalog in the 1980's. They changed their mind about producing them but the catalog was already printed.
The bottom line is this: Colt never sold any Pythons in any caliber other than .357 Magnum, and the Colt Python Target in .38 Special with an 8 inch barrel.
Anything else is either one of the prototypes from the Colt museum or it's a non-Colt conversion someone made.
This has gotten so bad, one owner of a .41 Magnum Python lettered it from Colt and it came back as a standard .357 Magnum.
He refused to accept this and swears that Colt is lying about making it for some reason.