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The black art otherwise known as “double rifle regulation” is not a reference associated with hunting, rather the term is used to define “point of impact” when a double rifle is being shot by its maker prior to completion for accuracy. Double rifles are indeed very special creatures, and require regulation for proper barrel convergence in relation to point of impact. It is true that a time method is used for the second shot upon regulating the given specimen. However, once this is done its done, unless you alter the load. So a second shot with a cold tube, should have basically the same point of impact as a hot tube in theory. Remember shots are usually taken within 10 to 30 paces with these guns. Regulation is done at 50 meters at the factory on anything over 375.

While the bullet is traveling down the right barrel (of a side-by-side double rifle) the rifle will be pushed up and to the right, throwing the bullet up and to the right when it exits the muzzle. While the bullet is traveling down the left barrel, the rifle will be pushed up and to the left, throwing the bullet up and to the left when it exits the muzzle. To compensate for the movement of a double rifle while bullets are traveling down the barrels, it must be built with the barrels converging towards the muzzle (by a mysterious amount). Because different powder charges, bullet weights, rifle weights, shooter body weights, ambient temperatures, etc., all effect the way a rifle moves under recoil, the only way to balance these factors is by trial and error. This process is called regulation. The goal of regulation is to make the rifle shoot both barrels to a common point of impact at a range appropriate for the calibre. One can proceed generally in either of two ways: adjusting the relative position of the barrels or adjusting the load. If one has a fixed load in mind, the former method must be used. It involves repetitive unsoldering and resoldering the barrels until the required convergence is achieved, then relaying the ribs and finally refinishing the barrels. A simpler method is to vary the load. The longer the bullet spends traveling down the barrel, the greater the force is exerted on the rifle to cause it to move while under recoil. If bullets from the left and right barrels strike the target too far apart at the desired range, and have crossed before they reach the target, the velocity is too great. The bullet weight must therefore be increased or the powder charge decreased. If bullets from the left and right barrels strike the target at the desired range too far apart, but have not crossed before they reach the target, the velocity is too slow. The bullet weight must therefore be decreased or the powder charge increased.

The construction of an effective double rifle is the apogee of the gunmaker's art. If, however, one comes into possession of a double rifle for which the original load is unknown, one can often make it shoot well by adjusting the load to the rifle.