Is it a bad idea? Should I send it away or can any gunsmith do it?

The biggest issue is refinishing the cut area, so while just about any gunsmith can turn it down, the barrel needs to be reparked afterwards.

.600 is the nominal barrel diameter of a lightweight contour barrel.  You'll need to ramp it down from full diameter near the upper to leave more meat around the chamber.

Unless you've got a good guy close to you for doing the turndown and repark, it might be a good idea to send it off to Kurt's Kustom - he does the turndowns all the time.