No. 1091 INSTRUCTIONS FOR PROOF OF GUNS md CARRIAGES INCLUDING STAR-GAUGING OF GUNS and TAKING IMPRESSIONS OF BORE {ONE PLATE) FEBRUARY 16, 1905 REVISED NOVEMBER 7, 1906 REVISED MARCH 11, 1908 REVISED JANUARY 28, 1913 REVISED JUNE 7, 1916 WASHINGTON GOVERNMENT PRINTING OFFICE 1916 I (Form No. 1091.) THE OFFICIAL NUMBER OF THIS COPY ■s 213 The Commanding Officer or the Post or Coast Defense Ordnance Officer to whom this copy is issued will be held personally responsible for its safe=keeping. When another officer relieves him a receipt for it by number will be taken, which should be mailed to the CHIEF OF ORDNANCE, U. S. Army, Washington, D. C. B ■ ■■■■-. NOTE. — This pamphlet may be destroyed when super- seded by one of later date. ( 2 ) U/VA?) P War Department, Office of the Chief of Ordnance, Washington, June 7, 1916. This manual is published for the information and government of the Regular Army and Organized Militia of the United States. By order of the Secretary of War: William Crozier, Brigadier General, Chief of Ordnance. 46153— IG ( 3 ) Digitized by the Internet Archive in 2016 with funding from’' University of Illinois Urbana-Champaign Alternates https://archive.org/details/instructionsforp00unit_1 GENERAL INSTRUCTIONS. 1. Before proof-firing, both gun and carriage should be carefully inspected, inspection blanks used by armament officers for semiannual inspections being taken as guides. Care should be taken that both are in perfect working order. Similar inspections should be made after the proof-firing, and reports made out giving all the informa- tion on the blanks referred to above, including items under firing; any breakage or irregular action of gun or carriage being carefully noted. 2. The proof-firing at fortifications will always be under the charge of the armament officer, except in special cases where authority to omit this requirement is obtained from the Chief of Ordnance. 3. The ammunition to be used in the proof -firing should be exam- ined by the proof officer to see that it is standard in all particulars; he should especially note the powder used to make certain that it is for the caliber and model of gun in which it is to be fired. 4. In all cases where new guns are fired, for whatever purpose, the gun will be star-gauged before firing, and again after comple- tion of the number of rounds prescribed for the proof of each gun, for the purpose of funiishing the data required for the inspection report. 5. Before star-gauging the gun the bore and chamber must be thorougldy cleaned in order that all residue or dirt may be removed therefrom. For this purpose special wire cleaning brushes have been issued to each district armament officer. Special cleaning tools for removing copper deposit and residue in extreme cases have been designed. If required, and not on hand in the armament district, application should be made to the Chief of Ordnance. Lavaline is also issued for use in cleaning the bore of guns. ^Vfter proof-firing, special attention will be given to the development of cracks in the tube, particularly near the muzzle end. Every defect discovered will be recorded, with such measurements or impressions taken as wiU enable any increase in its amount to be determined. 6. While the Ordnance Office will endeavor in some cases to pro- vide powder in advance of ordering material proof-fired, this should not be depended upon; the officer in charge of making these proof- firings should assure himself that the post is supplied with the neces- sary powder, and if it is not he should^ make requisition therefor. 6 7. Whenever a district armament officer is cognizant of the fact that armament in his district will soon be ready for proof-firing he should submit, in advance, a special requisition for the necessary powder charges. 8. Powder charges for proof-firing will be accompanied by a print of the charge-pressure curve of the powder in question, and the proof officer should have this in his possession or assure himself that it is at the post before proceeding thereto for proof-firing. The charges should be fired as issued unless it is apparent that the powder is giving consistently higher pressures than anticipated, in which case the larger charges should be reduced, using the charge-pressure curve as a guide. Unless the powder is giving pressures more than 5 per cent above those anticipated, it should not be necessary to reduce any but the 15 per cent excess pressure charge. INSTRUCTION FOR PROOF-FIRING OF GUN CARRIAGES. 1. Contracts for all carriages require that prior to acceptance they shall withstand the firing of a certain number of rounds at such place as the department may prescribe; this provision is sometimes waived to avoid too long withholding the final payment for the car- riage. In the case of seacoast carriages and in the absence of instruc- tions to the contrary, when a carriage is mounted in a fortification without having been previously proof-fired, the requirements as to proof thereof are considered as fulfilled by the following, viz : 2. Each gun and carriage after being mounted in a fortification shall be fired four rounds with charges giving pressures as follows : (a) Seventy-five per cent of maximum service pressure to be fired at such elevation as local conditions or data to be obtained make desirable. (b) Maximum service pressure to be fired at such elevation as local conditions or data to be obtained make desirable. (c) One hundred and ten per cent of maximum service pressure to be fired at the minimum elevation permitted by the carriage.^ id) One hundred and fifteen per cent of maximum service pressure to be fired at the maximum elevation permitted by the carriage.^ Each gun and carriage after having been disassembled and re- mounted in a fortification shall be fired two rounds with charges giving pressures as follows: (a) Seventy -five per cent of maximum service pressure to be fired at the minimum elevation permitted by the carriage.^ (b) Maximum service pressure to be fired at the maximum eleva- tion permitted by the carriage.^ 1 When local conditions do not permit firings at extremes of elevation with safety, elevations as near these limits as possible consistent with safety will be used. 7 The maximum service pressures referred to above are those given under the heading ^‘Maximum pressure’’ of the table under Ballistic Test — Ordnance Department Pamphlet 450, Specifications for Cannon Powder, except in proof-firing carriages for guns enumerated in table below the standard pressure will be that indicated opposite the re- spective guns. 3-inch (15-pounder) gun, model of 1903 40,000 5- inch guns, model of 1900 38, 000 6- inch guns, models of 1900, 1903, and 1905 39, 000 10-inch guns, model of 1900 38, 000 12-inch guns, model of 1900 39, 000 All 14-inch gun carriages, in addition to the prescribed proof rounds mentioned under a, h, c, and d of paragraph 2 above, will be fired an additional round with pressure approximately 47,000 pounds per square inch. In the absence of special instructions from the department, the proof of armament mounted in fortifications will be made as pre- scribed in this paragraph, excepting that the district armament officer may in special cases be authorized to fire such additional rounds as may be necessary in view of the results of the regular proof rounds. 3. Where the gun mounted thereon lias not previously been proof fired, all necessary data in regard to the operation of the carriage will be obtained from the firings required for the proof of the gun. 4. Prior to making the firings the following action should bo taken as far as applicable in each case, viz: (a) Adjust elevating friction device as prescribed in the handbook for the carriage. (b) Make similar adjustment for the traversing friction device. (c) Set throttling valve at zero, and see that it is properly assem- bled. (d) See that recoil cylinders arc properly filled. (e) See that all working parts of carriage are clean and well lubri- cated. 5. If the carriage has not previously been proof fired, the record of proof firing will bo entered in both copies of shop inspection report if available. If but one copy is available, a duplicate of the record of proof firing with all remarks as to breakages, etc., will be made out on Form No. 1116 and forwarded to the Chief of Ordnance for insertion in the original copy of the shop inspection report. 8 Inspection and proof reports — carriages. Form No. Designation of blank or description of work. 1069 1070 1071 1072 1084 1085 1086 1114 1115 1116 1117 1118 1120 1122 1123 1124 1134 1141 1144 1150 1152 1154 1161 1166 1167 Report of inspection of barbette carriages. (2 sheets.) Report of inspection of rapid-fire barbette carriages. (2 sheets.) Report of inspection of disappearing carriages. (5 sheets.) Report of inspection of mortar carriages. (2 sheets.) Inspection report of 6-inch diappearing carriages, Iv. F., model of 1903, No. — . Inspection and proof report of 3-inch gun carriage. No. — , model of 1902. Inspection and proof report of 5-inch barbette carriage, model of 1903. Inspection report of 12-inch mortar carriage, model of 1896, Mii. Inspection and proof report of 15-pounder barbette carriage, model of 1903, No. — . Report of inspection, gun and carriage, special sheet for firings. Recommendations and remarks. Inspection report of 12-inch disappearing carriage, L. F., model of 1901, No. — . Inspection and proof report of 4.7-inch gun carriage. No. — , model of 1906. Inspection report of 6-inch disappearing carriage, L. F., model of 1905, Mi, No. — . Inspection report of 12-inch mortar carriage, model of 1908. Inspection and proof report of 3.8-inch field howitzer carriage, model of 1908. Inspection and proof report of 6-inch howitzer carriage, No. — , model of 1908. Inspection and proof report of 14-inch disappearing carriage, L. F., model of 1907, No. — . Inspection and proof report of 4.7-inch howitzer carriage. No. — , model of 1908. Inspection and proof report of 6-inch disappearing carriage, L. F., model of 1905, Mii, No. — . Inspection and proof report of 3.8-inch gun carriage. No. — , model of 1904. Inspection and proof report of 6-inch barbette carriage. No. — , model of 1910. Inspection and proof report of 12-inch mortar carriage, model of 1896, Mm, No. — . Inspection and proof report of 3-inch mountain howitzer carriage, model of 1911. Inspection and proof report of 4.7-inch howitzer carriage, model of 1908, Mi. INSTRUCTIONS FOR PROOF FIRING GUNS. All guns, except type guns, should be proof fired the following number of rounds before acceptance, unless otherwise specified in the contract: 1. All 1-pounder guns and 1-pounder subcaliber guns, 10 rounds; 6 rounds with maximum service pressures, 2 rounds with 10 per cent above maximum service pressure, and 2 rounds with 15 per cent above maximum service pressure. 2. All guns of a caliber greater than 1 -pounder and less than 8 inches, five rounds — one round with half maximum service pressure, one round with three-quarters maximum service pressure, one round with maximum service pressure, one round with 10 per cent above maximum service pressure, and one round with 15 per cent above maximum service pressure. 3. Guns of 8-inch caliber and larger, four rounds — one round with three-quarters maximum service pressure, one round with maximum service pressure, one round with 10 per cent above maximum service pressure, and one round with 15 per cent above maximum service pressure, except 14-inch guns will be fired an additional round with pressure of approximately 47,000 pounds per square inch. 4. The maximum service pressures referred to above are those given under the heading ^‘maximum pressure” of the table under Ballistic Test — Ordnance Department Pamplilet 450, Specifications for Cannon Powder, except in proof firing guns noted below the standard pressure will be as follows: 9 3-inch (15-pounder) gun, model of 1903 40,000 5- inch guns, model of 1900 38, 000 6- inch guns, models of 1900, 1903, and 1905 39, 000 10-inch guns, model of 1900 38, 000 12-inch guns, model of 1900 39,000 5. Pressures should always be taken when proving guns, and each part of the gun or breech mechanism which is not in satisfactory work- ing condition should be reported upon. Whenever practicable the’ instrumental velocity of each round will be taken. 6. The gun should be star-gauged both before and after being proof fired. The same operator should, when possible, do the star-gauging for the same gun before and after, as it will insure the same touch on the micrometer handle. Inspection and proof reports, etc., guns. Form No. Designation of blank or description of work. 1096 2356 1077 1078 1079 Report of inspection and proof of — inch — , No. — , model of — . Extra sheet for Form No. 1096 for additional star-gauging records. Record of measurements of — inch — , No. — , model of — (shrinkage operations). Extra sheet for Form No. 1077. Do. STAR-GAUGING GUNS. Two sizes of star-gauges are in use in the service, one for measuring cannon up to and including 3 inches in caliber, and a larger one for measuring cannon of 3-inch caliber and larger. The larger star-gauge has two heads, one for measuring cannon of S-inch caliber and larger and one for measuring cannon of less caliber. The method of operating the two star-gauges is the same, except that with the smaller star-gauge bore rests are unnecessary and are not supplied. The star-gauge may be used as either a two or three point gauge by adjusting the head. When used as a two-point gauge four identical points are inserted in the head, a paper washer about 0.004 inch tliick being inserted under the two opposite ones used for measuring. The other two points act as guides and tend to keep the head centered in the bore. Except in special cases, the gauge is used with but two points, when the following instructions apply: To star-gauge a 12-inch gun, model of 1895, for instance, the method employed is as follows: The large star gauge is in sections, each 50 inches in length. To the head section, which carries the points, the additional sections are added until the gauge is of suffi- cient length for the gun. The micrometer handle is then screwed on, the scale on which should be in fine with the figures on the gauge. The entire gauge should be assembled in front of the breech end of the gun on the horses, the slides on which have been adjusted to the proper height. Insert into the sockets in the head four 12-inch points, placing the paper washers under the two opposite points that are to be used for measuring. Take the ring marked “ 12-inch, which is supplied with the gauge, and have it held by the assistant so that when the handle is turned forward the two measuring points will touch the inside of the ring, the latter being kept central by the other two points. With the gauge in this position adjust the handle so that it now reads zero. The muzzle rest is then adjusted on the breech so that its center is in the axis of the bore. The three arms of this rest are graduated, and the rest is properly located when the readings on all arms are the same. The gauge is now inserted in the bore and moved slowly forward, the points following the grooves, until it is at the extreme muzzle end of the gun. The gauge should be moved muzzleward until the head and points clear the bore, the measuring points turned horizontal and the head reinserted in the bore. The grooves and lands measured should be indicated by prick-point marks on the muzzle face, to insure the measuring of the same grooves and lands before and after proof firing. The operator, standing at the handle, turns it so that the two measuring points touch the bottom of the grooves, and the assistant, who is standing in rear of the rest, notes the number of inches from the breech. The scale of inches is on the gauge, and is adjusted so that the reading is taken flush with the rear face of the rest. The assistant calls off the distance and the operator the reading, which is in thousandths of an inch, plus or minus, depending upon whether the reading is greater or less than the ring by which the gauge was adjusted. The recorder enters these data in the book. The operator then turns the handle slightly, to take the pressure off the points and the assistant withdraws the rod 5 inches and calls off this dis- tance. The operator reads the measurement and calls it off, the recorder entering both in the book as before. This is repeated every 5 inches along the bore, until near the breech end, where it enlarges. From this point on the readings are taken every 2 inches. In the smaller caliber guns the readings along the entire length of the bore are taken every 2 inches. When inserting the gauge, after the 70-inch mark on the gauge has passed the breech, a bore rest is placed on the gauge just inside the muzzle rest. These rests are supplied with the gauge for each of the different calibers. They are placed every 70 inches, although near the handle this distance between the bore rests may be increased. If it is impracticable to measure the bore from the breech end, it may be measured from the muzzle, in which case the operation 11 is the same, except that the measurements are taken as the gauge enters the muzzle instead of as it is withdrawn. Plate No. 1 shows the bore of a 10-inch gun being star-gauged from the muzzle end. In this case it was impracticable, on account of obstructions, to meas- ure from the breech end. After completing this first measurement of the bore the gauge is turned 90°, so that the measuring points are vertical, and the opera- tion is repeated. This gives a vertical and a horizontal measure- ment of the grooves. The lands are then measured in the same manner, both a vertical and a horizontal measurement being taken. In measuring the lands, however, the proper guide plates must be attached to the end of the star-gauge head. The guide plate is secured to the head by four screws. The guides have grooves which fit over the lands, being forced outward by springs against the walls of the gun, and serve to keep the points on the lands. There is a guide plate for each caliber gun. Care should be taken to see that the guides have the same pitch as the rifling of the gun. After measuring the bore, the chamber is star-gauged. Remove all unnecessary sections from the gauge, as it will be easier to handle. Put on 14.2-inch points (in case of 12-inch gun), and again adjust the handle so that it will read zero when the ]u)ints are in the 14.2- inch ring. The measurements of the chamber should be taken every 2 inches, with the measuring points horizontal, and the same repeated with the measuring points vertical. The advantage of measuring the bore from the bree(‘h end is that, after measuring the bore, the chamber can be measured without changing the ])osition of the horses or of the muzzle rest, which is attached to the breech of the gun, thereby effecting a considerable saving in time. In star-gauging the chamber of guns in which the diameter of the powder chamber is contracted at the breech end, two or more special hinged points must be used. After the gauge has been adjusted by means of the pro])er ring, the hinged points are turned down to allow the gauge to enter the chamber, after which they are turned up and the star-gauging continued as in the ordinary case. When used as a three-point gauge aU points bear, and when meas- uring the lands all are supplied with guides. The same care must be observed in adjusting the guides as when two measuring points are used. Plate No. 1 shows the muzzle rest, the head section, and the points. Before star-gauging a gun, the bore and chamber should be thor- oughly cleaned, and, if necessary, aU copper deposits removed with a solution of sal ammoniac. The star-gauge is a delicate instrument and should be handled with the greatest care. All parts should be kept absolutely free from rust and the working parts should be oiled. 12 Star-gauge measurements pertaining to the manufacture or proof of a gun are entered on Form No. 1096, and those relating to subse- quent firings on Form No. 2356, which is practically a duplicate of the last sheet of Form No. 1096, to be attached thereto to complete the record of the gun. The practice at Sandy Hook Proving Ground is as follows: The rough record taken at the time of the star-gauging is entered in a small book furnished for this purpose by the department. This record is then entered in a large book, also furnished by the depart- ment, the measurements recorded being the mean of the vertical and horizontal measurements as recorded in the small book. The entries on the blanks referred to above are made from the large book, which is kept as a retained copy and permanent record. All the star-gauge records should give the distance from the face of the breech of the gun to the point measured, whether the original measurements have been taken from the breech end or from the muzzle end of the gun. When a star-gauge is adjusted to a standard ring by an operator other than an officer, and before measurements are taken, the officer in charge of the work will, whenever practicable, personally verify the setting of the micrometer handle and the use of the proper standard ring. The record book will show for each star-gauging of a gun: The name of the operator, the name of the officer verifying the adjustments, the temperature of the air inside and outside of the bore, the diameter of the standard ring used for each adjustment, the date and number of rounds fired from the gun. A page of the small record book and a copy of a portion of one of the completed star-gauge records are attached hereto. Measurement of 6-inch gun, W. A., No. 4, Model of 1897 Mi. [a page op small record book.] BEFORE FIRING. Inches from breech. Lands. Grooves. Vertical. Horizontal. Vertical. Horizontal. 27 7f 6. 0010 6.0030 6. 0030 6.0030 6. 0030 6.0020 6. 0020 6.0020 6. 0020 6.0010 6.0010 6. 0010 6 6 6.0800 6.0810 6.0810 6.0810 6.0810 6.0810 6.0810 6. 0800 6.0810 6.0810 6.0810 6. 0810 6. 0810 6.0810 277 275 270 265 260 255 Measurement of 6-inch gun, W. A., No. 4, Model of 1897 Mi — Continued. [a portion of one of the completed records.] Inches from breech. Lands. Grooves. Before firing, June 28, 1902. After 24 rounds, Oct. 10, 1902. Difference. Before firing, June 28, 1902. After 24 rounds, Oct. 10, 1902. Difference. 277.75 6.0015 6. 0025 6.0020 6.0020 6.0020 6.0010 6.0010 6.0015 6. 0020 6. 0020 6.0010 6.0010 6.0015 6.0015 6.0800 6.0810 6.0810 6.0810 6. 0810 6.0810 6.0810 6. 0810 6.0815 6. 0815 6.0810 6. 0810 6. 0815 6. 0815 +0. 0010 + .0005 + .0005 277 275 -0.0005 270 - .66i6 - .0010 + .0005 + . 0005 265 260 255 + .0005 + . 0005 DIRECTIONS FOR TAKING GUN IMPRESSIONS. Where a more minute examination of the l)oro of a gun is required than can be obtained hy simple inspection with the use of lights and a mirror, or whore the part of the lioro to bo examined is inaccessible to those means, an impression of the bore will be taken on gutta- percha. The following tools are required: One smooth board, about 15 by 26 inches, on which the gutta- percha is rolled. One roller of hardwood, for rolling the gutta-percha. One iron rod J inch in diameter and from 15 to 20 feet long. About 27 inches of this rod on one end should be threaded. Two nuts and washers to fit the aliove rod. One bar of iron 2 by 2 by 26 inches with a hole in the center inch in diameter. The iron rod above passes through this hole and a set screw in the bar holds it in place. One pole about 15 feet long with ferrule on one end to prevent its splitting. One kettle for heating water. A sufficient quantity of Dixon’s No. 634 graphite. In addition to the above, a block of pine wood must be prepared for taking the impression. This piece of wood should be long enough to get the impression desired, and its top surface should be cylindrical, with a radius \ inch less than the bore of the gun. Its top surface should be about one-third of the circumference of the bore or less. A yf-inch hole should be bored through the length of the block. The block should be 1 inch thicker at one end than the other, so that the lower surface will act as a wedge. (See sketch on next page.) In the top surface of the block should be drilled I-inch holes | inch deep, spaced about 2 inches apart. These have been found more effi- cacious than the two coats of shellac formerly prescribed to make the gutta-percha adhere to the block. Moreover, the time required for the shellac to drv is saved. 14 Gutta-percha on which the impression is made. (See note.) A wedge of hardwood is also required. This wedge should be the same length as the block, with its lower surface cylindrical, and of such a size that when the block and wedge are placed together, their ends flush, the combined diameter will be | inch less than the diam- eter of the bore. A hole is bored in the larger end of the wedge to take the end of the pole. The pole is driven into this hole and secured in place by a strong wood screw. Suppose it is desired to take the impression from the breech of the gun. The iron rod is placed with its threaded end through the hole in the block of pine wood and a nut and washer at each end oi the block are used to secure it in place. The unthreaded end of the rod should project from the small end of the block. The iron bar is then fastened to the rod, so that the distance from the bar to the middle of the block of wood is the distance from the breech of the gun to the center of the impression desired. The gun should be well cleaned and all oil carefully removed. The two wedge surfaces on the block of pine wood and the hard- wood wedge should be rubbed with tallow. Fill the kettle partly full of water and heat it to about 190° F. Place the gutta-percha in this hot water and let it remain there until soft. When soft place it on the board, which has been first wet with water, and roll the rubber out until it is of proper size. Care must be taken that the board is kept wet, and that the gutta-percha is of an even thickness; I inch is about right. The sheet of gutta-percha is then placed on the block and the edges trimmed off with a pair of shears. The top surface of the gutta-percha is then rubbed with graphite. The block is then placed in the gun, the bar locating it at the proper distance, and the wedge is driven into place. When cool, drive out the wedge, being careful that the impression is not moved until the wedge has been removed. The block with the impression is then carefully removed and trimmed. 15 The sketch below shows the parts assembled and in the gun. Note. — The only satisfactory gutta-percha obtained for the pur- pose at the proving ground has been purchased as ‘‘gutta-percha for taking gun impressions’^ from the Bishop Gutta-Percha Co., 420 East Twenty-fifth Street, New York City. It is furnished in slabs about 20 inches long, 5 inches wide, and f inch thick. War Department, Office of the Chief of Ordnance, Washington, June 7, 1916. February 16, 1905. Revised November 7, 1906. Revised March 11, 1908. Revised January 28, 1913. Revised June 7, 1916. 062.1-826 Revisions. Form No. 1091. Ed. June 7-16-500. O No. Preoaratorv to measurini? chamber.