Double rifles have nearly superseded single ones; for few who can afford the additional price will use the latter, when in the same weight he can have two useful weapons. The one great end generally sought in a rifle is sufficient weight to neutralise the force of the explosion or recoil; and the additional barrel answers this as effectually as additional thickness of iron in the single. But there is one objection which I have never been able to master in the construction of double rifle barrels, and I much doubt the possibility of effectually overcoming it--another proof that mathematical demonstrations are frequently wrong in practice, however correct in theory. Many hold it to be essential that double rifle barrels should be put together perfectly parallel. I followed this rule, and was at considerable cost in perfecting tools for the purpose; yet, strange to say, in trial I found invariably that the right barrel threw the ball slightly to the right, and the left to the left. This I have been at enormous trouble to ascertain, and am enabled positively to declare it is an indisputable fact. The cause of it is evidently the recoil not striking the stock in the centre, but on one side; which causes the gun to swerve to that side. However small or unapparent the recoil may be, still there is a recoil; and hence its effect. To remedy this it is necessary to incline the barrels in, towards the muzzle, to counteract that tendency; but in doing this another evil is created, for you can only do this to suit a given distance, either 100, 150, or 200 yards, as may be determined. Thus it will be perceived a deficiency must exist at all times; and it shows clearly the necessity for motion being resisted centrically, if truth is to be maintained. This defect in the double rifle will always be a drawback to the “_most correct_ shooting;” yet under ordinary circumstances it may not be a matter of vital importance, neither does there exist any means of sighting to overcome the difficulty. The only way to obtain a double rifle perfectly true--perfectly parallel, is to construct the barrels one above the other, as double pistols are now constructed. The only objection to them is the difficulty attending the arrangement of the locks, as one cock must strike the nipple the thickness of the barrel below the other, and is an unsightly matter at best. These facts lead to another, namely, the necessity of all rifles being stocked as straight as possible, avoiding in all cases any casting off in the butt; as it is evident that these matters have considerable influence on the correctness of shooting.