Sorry my ignorance Roland ...
Is this trigger set you refer the same resource as the so called 'hair trigger' ?. If so, isn't it more a device for (sports) target shooting ? I realized a heavy game gun like that of Jean-Luc is more like for 'crude' shooting; the target to aim at being large enough
Here is one with similar caliber (4 bore) and similar weight (7,7 Kgs.) made circa 1848 by Harris Holland for Sir Samuel Baker, who used to call it 'my baby'. It was damaged during an elephant charge and was repaired with elephant skin, covering the stock comb and lockwork.
(Courtesy "Oito SÚculos de Historia em Portugal").