Where none of these rules can be brought to bear it is but natural that the inexperienced gunsmith should turn to his Manual for aid in forming judgment upon the quality of the gun. A few general ideas may not be out of place.
All the movements of the action should be smooth, and all the joints should fit to perfection. The locks should have due consideration. When the hammer is drawn back it should come with less and less resistance as it rises, and vise versa when the hammer is let down, exerting its greatest power immediately on reaching the nipple or firing-pin. But this increase and decrease of power should be extremely gradual, and not great. Throughout the movement there should be a steadiness and freeness, or, as Gloan says, an oiliness, which when once realized, can never afterwards be mistaken. And when by a regular pressure upon the trigger the hammer is expertly raised and lowered in rapid succession, the locks should emit a clear ringing sound at the whole and half-cock with the resonance and regularity of beats in music. When once heard, this, too, can never afterwards be mistaken. The locks which perform to perfection under the tests mentioned are technically said to “speak well.”
Turning from the lock to the lever, the latter should close with such ease as not to require any particular exertion of the wrist, and when closed it should hold with such a degree of firmness as to place safety, while discharging the gun, entirely beyond question. The wedges of the action should be fully and squarely set in the lump.
If a pin gun the pin should fit in the hole with nicety. If too tight, the barrels might not close, or the pin might be held back to such an extent that the cap would not be exploded. If too loose an unnecessary escape of gas at the discharge would be unavoidable, to the discomfort of the gunner and the weakening of the shot.
If a central fire the plungers should strike the centre of the cap unvaryingly. The hammer should come upon the plunger with a blow—not a mere push.
The countersink of the chambers, and the length and breadth of the action bed, should be closely observed. The countersink should be cut clean and deep enough to take the rim of the cartridge without leaving the slightest projection—else the gun will not shut perfectly. But if, on the contrary, the countersink be too deep the cartridge comes back on the breech before the charge makes its exit, which increases the recoil and renders accuracy less certain.
The central fire strikers should not be too short, an imperfection which might cause the discharge of the gun while closing it. On the other hand, they should not be too long, as that would interfere with the free motion of the gun. In the case of a pin gun the pin should invariably stand in exact line with the hammer, otherwise the blow would be apt to bend it, and the chances for exploding the cap would be less certain.
There should be no crevices between the wood and iron. If any such crevice exists between the stock and the false breech it is likely that the wood was green when put up, which would settle it that the gun was not the work of a responsible maker, for no such person would work imperfectly-seasoned wood.
The extractor of the central fire should never be permitted to escape the closest scrutiny. It should work without the slightest hitch, and its arms should enclose about one-half of the cartridge rim. The countersink should fit the rim precisely, in order that there may be no slipping.