October Country produced a line of big bore, English style sporting rifles. The "baby" was .62 caliber 20 bore, then .66 caliber 16 bore, then .69 caliber 14 bore, then .72 caliber 12 bore, then .84 caliber 8 bore, then 1.00 caliber 4 bore.
The .62 through .72 calibers were rifles 1 turn in 104". The 8 bore and the 4 bore were 1 turn in 144". These guns weighed in around 18 pounds.
I have a double eight bore rifle that shoots a 835 grain .820 round ball over 300 grains of Fg powder. It does kick, but not all that bad. I can get about a dozen shots out of it before I start seriously flinching.
Joe Williams at the Gun Works and Oregon Rifle Barrel Co. has made a couple of 2 bore barrels (1.325 caliber) 8 ounce ball, and a fellow I know in Colorado has a underhammer gun with one of those barrels on it. He prefers to square off against someone like Lennox Lewis than to shoot it with a full charge, like 450 - 500 grains Fg. He says it is really tremendous.
Look forward to chatting about the big guns some more.
Big Smoke