My choice was a double 8-bore. Two shots, available, compared to a single 4-bore where the "gun bearer" carried the additional gun.

Some writers from those days considered the 8-bore adequate. With a 4-bore possibly contributing to physical harm to the shooter over time.

In the meantime before the mystical hidden 8-bore turns up, I will have to settle for my patheticly small 10-bore.