eightbore,
The set triggers on these guns are single set triggers, which are pushed forward to set. It is harder to get behind the rear trigger in order to set it, doubly so in very cold weather.

Raimey,
By locating the rifle barrel on the bottom, it puts less stress on the action, by locating it closer to the hinge point( but not as close to centerline of the scope). This would also hold for the Brno; but since they are "hell for stout" and lock up like a vault, they have enough strength to put the rifle barrel closer to the sights or scope.
Mike