Non-Parker barrels?

[Channing Greene, Sr]

Putting it all together, it appears that my gun, at some point in time, had the original barrels changed, and presumably not by Parker. Possible culprit: my father's brother was a machine shop owner and a gunsmith. But why would he change? Original barrels damaged? Change from 16 or 20 ga?(Can that even be done and keep the original action?) Unfortunately both individuals are long-deceased, taking the secret with them. I do know that Dad was quite successful in partridge population control in Vermont in the early '30s, using this weapon.
Assuming the gun is in good condition, which it is, can anyone give an idea of the price range it would bring?

[Bill Murphy]

Some pictures of the gun, serial number stamps, and barrel and action flats will tell us a lot about its originality. Obviously, the 222,000 barrels were not installed at the factory, but are factory barrels, most likely. You haven't even told us whether the other set is stamped with the original serial number or not. Pictures will give us clues about the general fit of the barrels and forends to the action.