Lawson C. Cummins Rifle Scopes
Lawson C. Cummins Rifle Scopes
The Duplex rifle telescopes, manufactured by Lawson C. Cummins, Montpelier, Vt., in different styles, suitable for use on any model of rifle, are highly prized by sportsmen. They are achromatic, in seamless browned steel tubes, with steel hangings that confine them closely and firmly to the rifle barrel, the elevations being obtained by adjusting the cross-line with a thumb-screw. The wind-gauge consists of a vertical line adjustable by a thumb-screw. A central point is placed at the top of the field of vision. When no wind or mirage exists the vertical line is set at this central point, but when the target shows that the bullet is being deflected by gravity and atmospheric conditions, while the central point is on the bull's-eye, set the vertical line to the point of deflection and the correction is exact. With this telescope the balance of the rifle is not perceptibly changed, the symmetrical appearance of the arm is unimpaired, the fragility not increased.
The microscopic vision of the sight avoids all blur and diffraction which are forever brooding on metallic sights, and the telescopic view of the game or target, almost annihilating distance, makes the directing of a rifle shot a simple act, performed with ease and certainty. The signal advantages of these telescopes over many others consist in the substantial nature of the telescope itself, and in its rigid attachments to the rifle barrel, its wide field of vision and high illumination, making it easy to do accurate work in a light so dim that nothing at all can be done with any open sight. Figure 5 shows a rifle mounted with an 18-inch, achromatic, duplex telescope sight. A practical method of setting the telescope where no special tools are at hand, is this: Place the rifle in a vise and arrange a blank bullseye on a white ground about thirty yards in front; have the bullseye almost, but not quite, as large as the field vision through the rifle bore, and place a white center, one-fourth of an inch in diameter, on it. Point the bore of the rifle exactly at this bullseye; now place the hangings on the telescope, and be sure to put the one with the lightest base in front, and turn the screws just barely sufficient to hold the telescope in position. Now place the hangings containing the telescope on top of the barrel and mark the position for the slots and look through the telescope. If the fixed globe on the vertical line points at same height as the white center in bullseye, cut the slots of equal depth; if it points above, cut the front slot deepest; if below, cut rear slot deepest. To ascertain how much, put a slip of metal under one hanging just sufficient to cause the globe to point at the white center and use it for the difference gauge.
Care must be taken in filing the slots to secure a nice fit and have both hangings in line. When the hangings are set in the barrel, insert the telescope and arrange it so that the vertical line exactly corresponds with a plumb line in front and pinch it with the two screws in the rear hanging. While it is thus held in this position, bore and tap the holes in the front end of telescope and insert the screws through the front hangings and the work is complete. It sometimes happens that rather steady shooting rifles do not shoot where the bore points; and should occasion require the changing of the direction of the telescope after being set, it is better to move the rear hanging, which should be fitted very close in the slot, as the barrel being heavy at that point gives it strength for a stronger grip than further forward. The hangings should be placed as far apart as is consistent with surrounding circumstances. All rifles shoot under the point at which the bore is aimed considerably more than the fall of the ball from gravity. This is owning to the crook in the stock and other reasons, but in this matter each rifle has its own peculiar habit. Perhaps an approximate average of a seven pound, 32-40-165 rifle would be three inches at thirty yards, and if it is desired to use the fixed globe for short-range shooting it is well to make allowance when setting the telescope. However, that is not material, as the cross-line is adjustable both above and below the globe. By raising or lowering the checknut on the elevating thumbscrew, the tension may be adjusted to suit any taste. The focus thumbscrew should be screwed in very tight to prevent the recoil from slipping the glass out of focus.
Farrow, Edward S. American Small Arms; a Veritable Encyclopedia of Knowledge for Sportsmen and Military Men. New York: Bradford, 1904. Print.
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