My 470 Westley Richards doubled on a cape buffalo we were following up in thick jungle - one shot hit the point of aim and the other went high.

At the time the PH was facing down the buff's mate who was threatening to charge - I didn't notice a thing but the other buff decided to leave post haste.

For the rest of the safari I had a nagging pain going down my left arm and 12 months later had to have a damaged disc removed from my neck.

NitroX suggests that there is double the recoil force - if you consider recoil is measured by energy (rather than momentum) then the recoil is four times the energy of a single barrel discharge as the recoil velocity is doubled.

mike