Nitro you are absolutely correct and so is the fact that properly regulated double rifles do not cross the centers of each barrel’s individual group. This statement is what people are confusing as being bullet flight path!

This is the reason that most people have trouble trying to find a regulating load for a double rifle. They think no bullet should ever cross, and that is simply silly!

The factory regulator is not looking for all the bullet holes but is regulating the CENTERS of EACH barrel’s individual four shot group.

It stands to reason that if each barrel is shooting a 1 inch individual group and if the center of the bores are only 1 inch apart to form a composite group of both barrels, the right side of the left barrel’s group will spill over into the left side of the right barrel group and vise-versa.

When a double rifle is properly regulated the aiming point on the target should be half way between the CENTERS of BOTH barrels in the composite group.

If that regulation is at say 100 yds both those barrels that were shooting 1 inch groups at 100 yds will be shooting 2 inch groups at 200 yds, so now what you have is 4 or 5 inch 8 shot composite groups at 200 yds. But the centers of each barrel’s individual group will remain on it’s own side of the aiming point ( or parallel). Of course nobody can hold that well, but the rifle is capable of holding to it’s regulation indefinitely.

This why I’ve always said the test target that comes with a new double rifle tells you absolutely nothing and is nothing more than window dressing. This because a target that is worth anything should have four shots from each barrel all fired from cool barrels, with each shot marked as to the barrel it came from, and the centers of each barrel’s individual group marked for each barrel in relation to the aiming point.
The reason most think that a double rifle is regulated to cross at a given distance is the fault of the maker’s habit of labeling two different things as REGULATION. The regulation done by the regulator is the physical manipulation of the barrel conversion so that the rifle will shoot the centers of each barrels group on it’s own side of the aiming point. The have to converge so they will shoot parallel because of barrel flip and barrel time. Then the maker files the iron sight to a dead on hold point of aim at a given range, for elevation and windage and call that regulation as well. This makes the new owner want to make all bullets fired to hit the same hole on the target at that range which is wrong. If all bullets from both barrel were hitting the same ragged hole at any range the rifle would have the centers of both barrels individual groups CROSSING at that range.

In other words what is parallel is the CENTERS of each barrel’s individual groups that should remain parallel, not all the bullet holes!