Surge45

Its simple, the vast majority of double rifles were regulated to shoot the front trigger/right barrel first, and rear trigger/left barrel second.

I had a good discussion with one of the regulators/gunsmakers - Rico - at the Heym Gunmakers in Germany last month. And how barrels work during the shooting of the two barrels, timing between shots etc.

So shoot it first, front trigger then rear trigger, and that is how it should regulate most correctly.

Try it the other way round too, try it with the rear trigger, then the front, and see how it performs.

The reason many people shoot the rear trigger first, is because many shooters when firing the first trigger, under recoil tap the rear trigger and set off the second barrel as well.