Trouvé sur le net (américain...). C'est en anglais, mais ça donne une bonne idée du défi et des coûts qui, à mon avis, sont hors de proportion:
"First, Colt Python barrels are crush fitted, (like all Colt barrels). Attempting to remove the barrel without the correct tooling is guaranteed to ruin the frame. (No I'm not exaggerating, see the tool list below).
After removing the old barrel, the new barrel must be preped correctly, then the shoulder must be cut in a lath so the front sight indexes properly, and the shoulder must be undercut so it will "crush fit" properly.
The barrel is screwed on, and torqued properly, and indexed.
The rear of the barrel is trimmed with a special tool to set the correct barrel-cylinder gap.
The forcing cone at the rear of the bore must be properly cut with a special tool.
Attemping to do this without the correct tooling, the knowledge of the correct methods, and specifications, and the gun AT BEST won't shoot worth a damn, and AT WORST can be dangerous. In either case you will have a ruined expensive gun.
For complete info on the correct methods, tooling, and specifications, invest $25.00 or so in a copy of Master gunsmith Jerry Kunhausen's Book on Gunsmithing the Colt Revolvers, Volume One,( the Colt Python and Detective Special guns).
The tools can be fairly expensive, and attempts to use "expediant" methods like the infamous "hammer handle through the frame" trick is a sure method of destroying a fine Colt.
Among others, the needed tooling is:
A correct barrel vise insert, along with a BIG vise to hold it.
A correct frame wrench with correct Colt inserts.
A piloted,through-the-bore barrel face cutting tool.
A piloted forcing cone cutting tool kit, including the proper polishing heads.
No joke, this is a BIG job that looks fairly simple, and is easy to botch.
If you have gunsmithing experience, Kunhausen's book, and the tooling, you can do the job corrrectly. However, don't take chances with Python's, their too expensive.
In my experience, the people who get in trouble are the ones attempting to fit used, possibly damaged or defective barrels, and using improper tooling. The worst ofenders are those with the attitude that "it's just a threaded pipe, screw it off and screw the new one on".
You sound like you've got the right atttitude, so buy the Kunhausen book and the tools, and have at it."
a schöner gruess vum enn elsaesser wo im Kebec laebt. Minner rotschlaa isch: käuf d'r eher a nawell neiyi bischdol.