I regulate the barrels of the double rifles I build at 100 yards and at 50 yards. I first regulate the shots to just touch or maybe be 1/2" apart at 100 yards and then I check the shots at 50 yards to see the difference of what the 100 yard shot pattern. In general the 50 yard shots will pattern about 1 inch apart center to center. I also regulate the barrels for the shots to be nearly exactly the in the same horizontal plane.

I do not regulate them to shoot the right barrel or left barrel first. I regulate them to shoot perfect shots whichever barrel you shoot first; and during regulation I will shoot just about as many by shooting the left barrel first as I do shooting the right barrel first.

It takes a great deal of time and ammunition to regulate barrels to shoot with accuracy that I set as my goal and one rifle it took 300 rounds (I was developing a new cartridge), so I believe few people will/do likely regulate to this accuracy.

I also use the Holland & Holland style muzzle bridge to retain the barrels in place ---not the method of driving a wedge and soldering it in place--but making bridge the exact distance apart measured in thousands of an inch after using the temporary "solder in place" wedge to get the correct distance apart. I measure the distance of the barrels at the muzzle when I have reached my goal of accuracy at 100 yards and I make a Holland & Holland bridge on my milling machine for that distance; and sometimes I will have to make 2-3 of these bridges because only .001" to .002" distance apart makes significant differences at 100 yards. For those of you who do not understand the Holland & Holland double rifle bridge system view the video "A Look Inside Holland & Holland" and watch Steve Cranston regulate a double rifle. With the Holland & Holland muzzle bridge you never never have to be concerned with barrel movement in even the most severe and rough shooting conditions.

Double rifles can be found that have decades of use and the right barrel is worn out while the left barrel is still good. In my opinion shooters should make certain they shoot the shots from the barrels right and left--left and right in order to maximize barrel life.

I do not recall Graeme Wright discussing right/left of left/right barrel shooting.

Kindest Regards;
Stephen Howell