He loads the first two simultaneously (spelling?), one with each hand whilst the weapon is resting. There's no way that you're going to be able to hold a steady aim for long unsupported. Especially when you've got short arms like me.
It must be designed for rich blokes who are crap shots - six shots rapid fire for one animal?
I would have thought it would be less ostentatious to do it the tried and tested way: left and right from your old English nitro express rifle, then - if really necessary - get your man to hand you the second rifle....
We poorer types can make do with a smellie and some solid-nose .303.... (memories of a mis-spent youth in Africa...!)