Elric
Well-Known Member
A Direct-Reading ’Scope Mount By W. S. Belding
American Rifleman, Vol. 69, No. 18 June 1, 1922, page 15
https://books.google.com/books?id=g...6AEIUDAH#v=onepage&q=rifle micrometer&f=false
In developing a set of Telescope Mounts, considerations such as cost, accuracy, and convenience conflict. What seems most desirable for the Model 1903 rifle becomes an unnecessary expense if applied to a twenty-two.
I use three different mounts which we will designate as A, B, and C. “A” Mount is not illustrated and is practically the same as any standard front mount. Merely a hole for the scope which acts as the center of movement, without any adjustment.
“B” differs from the usual rear mount on the market in a number of respects. The micrometer barrels are separate from the micrometer screws but can be locked to the screws in any desired position. This feature allows the Zero mark on the drum or barrel to be brought to coincide with the Zero mark on the frame of the mount after the scope has been set correctly for a minimum range no matter where the micrometer screws are necessarily located. This .mount “B” has greater latitude of adjustment (in both elevation and windage) than any other. There is a difference in the contact between mount and dovetail blocks in these mounts, the contacts are on the bevel sides and not on the top of the dovetail blocks. They clamp on, so get contact on both of the bevel sides. The barrel of the micrometer is divided into fifteen divisions instead of the usual twenty five. Each division gives a change of point of bullet impact of one inch per one hundred yards. These divisions are so coarse that it is perfectly practical to split them by eye and get the so called one-half minute of angle.
By the way, regarding this minute of angle business. We have all been told that a minute of angle equals one inch per one hundred yards. The error in that statement is so great that I have discarded it in favor of the phrase “change of one inch in point of impact per one hundred yards.” The error is “.044” at 100 yds. and that is not much, sometimes, some places, but when multiplied by 10x10, for instance, becomes a factor requiring recognition.
Mount “C" differs from “B” only in details of elevation micrometer, which in this case is not a micrometer, as it does not read in thousandths. The screw is 10thd per inch instead of the usual forty. The thread is quadruple and the drum or barrel is one inch diameter by one-half inch high and is calibrated to read in yards from one hundred to two thousand yards, without the use of a table and without any calculation whatever. It is very carefully calibrated from the table of angles of departure and follows that table in accuracy. As you know, that angle of departure table for the Model 1903 has been proven correct up to twelve hundred yards, and is theoretically correct between twelve hundred and two thousand yards. These calibrations are on a replaceable, interchangeable thin tube and of course are only for Model 1903 with standard ammunition, i. e., twenty-seven hundred f. s. and one hundred fifty grain Spitzer bullet, but with an extra tube, which may be a rolled up sheet of paper, celluloid or sheet metal, one can easily calibrate a drum for his own reload or for the latest match ammunition with its heavier bullet and flatter trajectory.
Now, for all rifles except the Model 1903, I use “A” front and “B” rear mount as follows: Adjust the screws of mount “B" until the point of sight and the point of impact coincide at the shortest range at which you will normally use the rifle, then loosen the barrels of micrometers, moving them on the screws until the O on the barrel coincides with the O on frame of the mount. Clamp them tightly and Zero equals Zero and all changing of ranges are from a Zero base and easy to figure.
But for Model 1903 rifle the best combination of mounts is the direct reading mount “C” for front mount and mount “B" with its one inch per hundred yards change of point of impact divisions for rear mount, use as follows: Setting front mount at one hundred yards and scope central (as to windage) I hie me out to the range and adjust rear mount “B” until the black is found which usually requires two shots, never more than three shots. Then releasing barrels of windage screws on both mounts and of the elevation screw on the rear mount we set them all so the O on the barrels each agree with the O on the frame of the mount. Clamp tightly and there after we use the front mount when changing ranges and the rear mount with its finer corrections to make any necessary alterations. This seems to me an ideal long range hunting sight.
I have no mounts for sale. The scopes, bases and mounts have all been made as models and for my own guns but if the opportunity to manufacture does rap at my door, I believe we can furnish a pretty nice line of Scopes and Mounts.
American Rifleman, Vol. 69, No. 18 June 1, 1922, page 15
https://books.google.com/books?id=g...6AEIUDAH#v=onepage&q=rifle micrometer&f=false
In developing a set of Telescope Mounts, considerations such as cost, accuracy, and convenience conflict. What seems most desirable for the Model 1903 rifle becomes an unnecessary expense if applied to a twenty-two.
I use three different mounts which we will designate as A, B, and C. “A” Mount is not illustrated and is practically the same as any standard front mount. Merely a hole for the scope which acts as the center of movement, without any adjustment.
“B” differs from the usual rear mount on the market in a number of respects. The micrometer barrels are separate from the micrometer screws but can be locked to the screws in any desired position. This feature allows the Zero mark on the drum or barrel to be brought to coincide with the Zero mark on the frame of the mount after the scope has been set correctly for a minimum range no matter where the micrometer screws are necessarily located. This .mount “B” has greater latitude of adjustment (in both elevation and windage) than any other. There is a difference in the contact between mount and dovetail blocks in these mounts, the contacts are on the bevel sides and not on the top of the dovetail blocks. They clamp on, so get contact on both of the bevel sides. The barrel of the micrometer is divided into fifteen divisions instead of the usual twenty five. Each division gives a change of point of bullet impact of one inch per one hundred yards. These divisions are so coarse that it is perfectly practical to split them by eye and get the so called one-half minute of angle.
By the way, regarding this minute of angle business. We have all been told that a minute of angle equals one inch per one hundred yards. The error in that statement is so great that I have discarded it in favor of the phrase “change of one inch in point of impact per one hundred yards.” The error is “.044” at 100 yds. and that is not much, sometimes, some places, but when multiplied by 10x10, for instance, becomes a factor requiring recognition.
Mount “C" differs from “B” only in details of elevation micrometer, which in this case is not a micrometer, as it does not read in thousandths. The screw is 10thd per inch instead of the usual forty. The thread is quadruple and the drum or barrel is one inch diameter by one-half inch high and is calibrated to read in yards from one hundred to two thousand yards, without the use of a table and without any calculation whatever. It is very carefully calibrated from the table of angles of departure and follows that table in accuracy. As you know, that angle of departure table for the Model 1903 has been proven correct up to twelve hundred yards, and is theoretically correct between twelve hundred and two thousand yards. These calibrations are on a replaceable, interchangeable thin tube and of course are only for Model 1903 with standard ammunition, i. e., twenty-seven hundred f. s. and one hundred fifty grain Spitzer bullet, but with an extra tube, which may be a rolled up sheet of paper, celluloid or sheet metal, one can easily calibrate a drum for his own reload or for the latest match ammunition with its heavier bullet and flatter trajectory.
Now, for all rifles except the Model 1903, I use “A” front and “B” rear mount as follows: Adjust the screws of mount “B" until the point of sight and the point of impact coincide at the shortest range at which you will normally use the rifle, then loosen the barrels of micrometers, moving them on the screws until the O on the barrel coincides with the O on frame of the mount. Clamp them tightly and Zero equals Zero and all changing of ranges are from a Zero base and easy to figure.
But for Model 1903 rifle the best combination of mounts is the direct reading mount “C” for front mount and mount “B" with its one inch per hundred yards change of point of impact divisions for rear mount, use as follows: Setting front mount at one hundred yards and scope central (as to windage) I hie me out to the range and adjust rear mount “B” until the black is found which usually requires two shots, never more than three shots. Then releasing barrels of windage screws on both mounts and of the elevation screw on the rear mount we set them all so the O on the barrels each agree with the O on the frame of the mount. Clamp tightly and there after we use the front mount when changing ranges and the rear mount with its finer corrections to make any necessary alterations. This seems to me an ideal long range hunting sight.
I have no mounts for sale. The scopes, bases and mounts have all been made as models and for my own guns but if the opportunity to manufacture does rap at my door, I believe we can furnish a pretty nice line of Scopes and Mounts.