The barrel set is placed in a jig, and the wedge, and spacers are soldered in, and ribs laid, with the barrels converging at an educated guess convergance to start with. The rifle is then taken to the range by a person, and fired by a person, and is held in the manner one would hold the rifle while shooting off hand. This is done with a standing rest, but nothing is touching the rifle but the person doing the "SHOOT-IN". In most cases four shots are fird with a known load, two from each barrel, in the order of rt,lft,rt,lft. Each shot is plotted on the target in it's order, and the speed of each shot plotted by cronograph. The target is studied by the regulator, and if it is fine, which is rarely the case, approximately ten shots, five from each barrel,will be fired to make sure the first four was not a fluke,if still OK, then regulation stops there. The rifle is sent to the finishers. If it isn't OK, then the barrel set is placed in an adjustment jig, for adjustment. The solder is softened by one of two ways torch, or heated bore diameter rods inserted into the muzzle end of the barrels. The most, common heat method is a jig over a burner, but the best is the rods. With the rods, one can re-regulate a already finished rifle without even damageing the blueing on the barrels or ribs, this is the method used by Holland & Holland. The solder is heated, and a series of screws are tightened, or loosened while the solder is soft, then alowed to cool naturally. The process starts all over again, till the desired conversion is achieved.

I've regulated several doubles, and re-regulated several others, and one never knows how many shots will be fired. A person like JJ from Camplins can often regulate with no more than 10 rounds because he usually gets it right the first time, and the last six are simply MAKE SURE rounds. I, OTH, usually use several more, but even I, have never used more than twenty! Stop and think for a moment, at over $10 per shot for factory ammo for a 470NE, twenty shots is a factor.

I find the hardest to get regulated are not the hard kickers, but the fast rounds like 300 FL mag, or even the little cartridges like the 225 Winchester, because the barrel time is so short, that the adjustments are so tiny that it is very easy to over adjust, requireing more backward adjustments. The big slow ones are easier, at least for me!

I hope any of this helps you, and I'm sure there aothers here who fit the expert qualification, that can tell you far better than I, and quite possibly with far fewer words!