The newer ones, both hammerless and hammer guns, often had "70" engraved on the rib extension to denote 2.75" chambers. I own/have owned a ton of them from 1880 to 1960's. A couple dozen maybe? Bought another one today as a matter of fact. Great guns, based on Sauer actions and high quality Swedish steel barrels. Hence, beefy and hell for stout.