Elric
Well-Known Member
It seems like I have a fairly good handle on the period barrel straightening stuff, or at least as far as I really wanted to know. There is a cut in a Harper's Weekly where the straightener has a mirror on the floor so he can sight DOWNWARD instead of holding the barrel slanted upward, but otherwise the methods seem the same.
Setting Or Straightening Gun-Barrels.
The Gun and Its Development: With Notes on Shooting, By William Wellington Greener
https://books.google.com/books?id=LAsAAAAAQAAJ&pg=PA270&dq=straight+barrels&hl=en&sa=X&ved=0ahUKEwjul6Pnw87PAhVh44MKHbKACbcQ6AEILDAD#v=onepage&q=straight barrels&f=false
Page 269-271
Previous to 1795 all gun-barrels were comparatively crooked, there being no reliable method of ascertaining when the barrels were straight. The usual way was to look along the outside, and set them as straight as possible from the outside. About 1795, however, a barrel-maker of Birmingham, named Parsons, introduced a plan of straightening barrels from the inside. His method consisted in stretching a string or fine wire inside the barrel from end to end, and touching the side at each end. He then hammered that side of the barrel until it touched all along the string. The string was then moved to the opposite side of the barrel, and if it touched all along the string it was straight. The same process was repeated on the top and bottom sides of the barrel. A few years afterwards, the method of shading the insides of gun-barrels was discovered. This simple and reliable plan has since been universally adopted as the standard.
To determine if a barrel is straight, the setter holds it a few inches from his eye with one end pointing towards the top of a high shop window. The rays of light being horizontal, and the barrel at a slight angle, it shows about half the bore in shadow ; if the shade is irregular the barrel is crooked ; if the shade is perfectly level from breech to muzzle, on the barrel being turned round, the barrel must be a perfectly straight one. To straighten a barrel, the setter should note where the swellings appear on the shade, and strike the barrel in that place with a hammer upon a hollow anvil. Some setters straighten from the indentations in the shade, in which case the barrel must be struck on the opposite side to the one shown on the indentation in the shade.
A skilful setter can make a barrel perfectly straight with a few taps of the hammer. The fine-boring bit having a perfectly straight cutting edge of eighteen or twenty inches, tends in a great measure to set the barrel tolerably straight. The barrel being thin the greater part of its length, it gives considerably to the bit. A simple expedient for detecting the straightness of a gun-barrel is as follows :—Place the barrel at a slight angle upon two fixed stands ; take a small frame and cover with tissue-paper, and place the same at about six feet distance from the muzzle of barrel with a light behind it ; point the barrel towards the top edge of frame, and a dark shade will at once be seen upon the bottom side of the barrel.
Turn the barrel round upon the stands, and if the shade keeps a perfectly true edge, the barrel is straight. Place at any point between the stands, about three inches below the barrel, a lighted lamp or candle. This will cause the barrel to bend, and an irregularity in the shade line will be immediately observed ; upon the light being removed, the barrel will return to its original form, or very nearly so. If the barrel is of steel (as a rifle-barrel), and not twisted, it may be experimented upon with the candle four or five times, and the barrel will return to its original straightness. A twist barrel but very seldom altogether recovers its original form after having been drawn by the heat. This proves that barrels should never, be heated to a red-heat after the boring is finished. It is a common practice with foreign makers to braze their barrels together from end to end. This is most injurious, as the barrels cannot be perfectly straight when so treated. The first order for Government rifles was received in Birmingham about 1816, and at that time setting or straightening was so little known that many of the barrels were far from being straight.
The importance of this invention cannot be overrated, as without it it would be impossible to obtain the extraordinary precision of the match rifles of England and America.
Upon the examination of a fine public collection of ancient small-arms by a practical man, it was found that out of the whole collection there was but one barrel that was, or had been, anything approaching to perfect straightness ; whilst the greater number deviated greatly from the straight line. The arms themselves are marvels of mechanical ingenuity and skill, and are the work of the leading and most renowned gunmakers of Europe, and finished in the most elaborate and artistic style, proving that they had been veritable armes de luxe.
Setting Or Straightening Gun-Barrels.
The Gun and Its Development: With Notes on Shooting, By William Wellington Greener
https://books.google.com/books?id=LAsAAAAAQAAJ&pg=PA270&dq=straight+barrels&hl=en&sa=X&ved=0ahUKEwjul6Pnw87PAhVh44MKHbKACbcQ6AEILDAD#v=onepage&q=straight barrels&f=false
Page 269-271
Previous to 1795 all gun-barrels were comparatively crooked, there being no reliable method of ascertaining when the barrels were straight. The usual way was to look along the outside, and set them as straight as possible from the outside. About 1795, however, a barrel-maker of Birmingham, named Parsons, introduced a plan of straightening barrels from the inside. His method consisted in stretching a string or fine wire inside the barrel from end to end, and touching the side at each end. He then hammered that side of the barrel until it touched all along the string. The string was then moved to the opposite side of the barrel, and if it touched all along the string it was straight. The same process was repeated on the top and bottom sides of the barrel. A few years afterwards, the method of shading the insides of gun-barrels was discovered. This simple and reliable plan has since been universally adopted as the standard.
To determine if a barrel is straight, the setter holds it a few inches from his eye with one end pointing towards the top of a high shop window. The rays of light being horizontal, and the barrel at a slight angle, it shows about half the bore in shadow ; if the shade is irregular the barrel is crooked ; if the shade is perfectly level from breech to muzzle, on the barrel being turned round, the barrel must be a perfectly straight one. To straighten a barrel, the setter should note where the swellings appear on the shade, and strike the barrel in that place with a hammer upon a hollow anvil. Some setters straighten from the indentations in the shade, in which case the barrel must be struck on the opposite side to the one shown on the indentation in the shade.
A skilful setter can make a barrel perfectly straight with a few taps of the hammer. The fine-boring bit having a perfectly straight cutting edge of eighteen or twenty inches, tends in a great measure to set the barrel tolerably straight. The barrel being thin the greater part of its length, it gives considerably to the bit. A simple expedient for detecting the straightness of a gun-barrel is as follows :—Place the barrel at a slight angle upon two fixed stands ; take a small frame and cover with tissue-paper, and place the same at about six feet distance from the muzzle of barrel with a light behind it ; point the barrel towards the top edge of frame, and a dark shade will at once be seen upon the bottom side of the barrel.
Turn the barrel round upon the stands, and if the shade keeps a perfectly true edge, the barrel is straight. Place at any point between the stands, about three inches below the barrel, a lighted lamp or candle. This will cause the barrel to bend, and an irregularity in the shade line will be immediately observed ; upon the light being removed, the barrel will return to its original form, or very nearly so. If the barrel is of steel (as a rifle-barrel), and not twisted, it may be experimented upon with the candle four or five times, and the barrel will return to its original straightness. A twist barrel but very seldom altogether recovers its original form after having been drawn by the heat. This proves that barrels should never, be heated to a red-heat after the boring is finished. It is a common practice with foreign makers to braze their barrels together from end to end. This is most injurious, as the barrels cannot be perfectly straight when so treated. The first order for Government rifles was received in Birmingham about 1816, and at that time setting or straightening was so little known that many of the barrels were far from being straight.
The importance of this invention cannot be overrated, as without it it would be impossible to obtain the extraordinary precision of the match rifles of England and America.
Upon the examination of a fine public collection of ancient small-arms by a practical man, it was found that out of the whole collection there was but one barrel that was, or had been, anything approaching to perfect straightness ; whilst the greater number deviated greatly from the straight line. The arms themselves are marvels of mechanical ingenuity and skill, and are the work of the leading and most renowned gunmakers of Europe, and finished in the most elaborate and artistic style, proving that they had been veritable armes de luxe.