This pair is 12 bore - roughly .720 caliber. I expect the recoil would have been ferocious - but perhaps a little less ferocious than a tiger in one's lap!
My Cashmore is the Nitro model. It is a rare design with exterior locks reinforcing the underlugs. They were made for a short period before WWI and were designed for the heavy 1 1/4 ounce loads that were used in the pigeon ring to decisively knock the birds down before they exited the ring. The chamber is actually a little longer than 70mm, but it is proofed for 1 1/4 ounce loads. The slightly extra length was to act as an extended forcing cone causing less shot deformation and extending the recoil impulse. I have shot this one in competition a lot and it has accounted for many hundreds of pheasants.
