Researcher will chime in with all the history and details, as my memory is a bit fuzzy; but as I recall, the purpose of the 3 1/2" 10-bore shell was to duplicate the payload of the outlawed 8-bore. I've got a few neat old roll-crimped Remington 8-bore shells, some 3 1/4" and some 3 1/2" in length (that would be the fired length). The longer shells have only a shot size stamped on the over-shot wad; but the over-shot wad on the shorter cases note the payload as 1 3/4 oz; so I assume the longer cases must carry a 2 ounce payload, which would indeed match the payload of a vintage 3 1/2" 10-bore mag. But nowadays, I see 3 1/2" 12-bore payloads at 2 1/4 ounce; so in my convoluted opinion, politicians, to be consistent, should either outlaw all 3 1/2" 10 and 12-bore loads that duplicate and/or exceed the outlawed 8-bore, or legalize/legitimize the old 8-bore. But then, in this real world, I do not expect common sense or consistency from politicians.
