My 340PD has a bit over two thousand through it. Most is 357 cases loaded to 38+p or 38++++p; maybe 10% real 357 (140-170 grs).
The cylinder is stained; the front, heavily; the sides, somewhat. I don't care.
There is no 'wear' that I can detect in anything other than the finish of the gun where it has gone in & out of OWB and pocket holsters in which it has spent hundreds of hours.
Treat it right, and it's the greatest balance of power, reliability, and ease of carry on the market, period.