[quote=“genkideskan”]When loading benchrest ammo it is common to mark the cases - than in the loading process the cases where always set by this mark- and of course you load the cartridge always with this mark at the same location- may be to the top. So the ammo was loaded and fired - always in the same position and that improve accuracy.
May be this is a positioning mark too- may be this marked rounds are for the right or left barrel or should be loaded with this mark to the top.[/quote]
I don’t think so, as these were / are all old black powder, or perhaps nitro for black, dangerous game loads & all double rifles should have the barrels “regulated” when made. IE; both barrels shoot at the same point of impact at the different sight ranges. Often the load was printed on the gun case label with a specific bullet weight and powder charge, even specifing the type of powder.
Personaly I would not want to be trying to kill one of the ‘big 5’ knowing I had to keep my ammo oriented for either left or right barrel when I had to reload. It was, & is, common for the double rifle hunter to carry 2 extra rounds between the fingers of the non-trigger hand for easy & fast reloading in case of a charge.