If gunsmith alters a chamber, but doesn't change cal. is he required to stamp the barrel?
Saw a Browning 1885 that was a 45-70(and is marked that way)chamber has been altered to a 45-120?????

I would think so. Don't see any reason why they wouldn't.

Do not think it is required but would be very smart to do so.

Although I haven't looked up the statute I'm told by reliable source it is required by Federal Law. Frankly, I don't give a damn about it being law, it's common sense.

I'll go with what John says.

You run into this sometimes. Quite a few people have had 458 rechambered to Lott, and the barrels are not always remarked. I had a 45-70 Ruger rechambered to 45-120 years ago when BELL first reintroduced the cases. The smith didn't mark it, but it made little difference, as both would chamber and shoot without a problem, much like the 458/Lott.

While in Gunsmith school I rechambered a 45-70 86 Winchester to 45-90 and there was considerable discussion at the time whether to stamp a 9 over the 7 or just leave it as it was. This was a rather deluxe 86 with set trigger shotgun butt fancy checkered wood and special sights. Decided it would look crummy if overstamped so left it as 45-70. I think it was the right decision at the time. Today I would make an effort to find the absolute proper 9 stamp and overstamp it.