Question on the 2 3/4"-70MM chambers: When did 2 3/4" 16 and 20ga shells first appear? Anyone with very old catalog information? We know that in the case of the 16ga, American guns weren't factory chambered 2 3/4" until the 20's (even 30's in the case of some companies). Concerning 20's, the Winchester Model 12 started out as a 20ga--chambered 2 1/2". Makes me wonder about pre-WWI European guns, especially smaller bores, with 70MM chambers. Were they shooting 2 3/4" back then? Something doesn't add up here.
