Chapter IX

SPECIFICATIONS FOR THE MANUFACTURE AND INSPECTION OF RUSSIAN 3-INCH SHRAPNEL AND HIGH-EXPLOSIVE CARTRIDGE CASES

The following specifications are abstracted from the official specifications for the Russian brass cartridge cases for 3-inch shrapnel and high-explosive shells, and contain all the essential information relating to the requirements in the manufacture and inspection of these cartridge cases.

=Clause 1. The Rights and Duties of the Inspector.=--The inspector’s duty consists not only in acceptance of the cartridge cases manufactured, but also in looking after the methods used in the manufacture of the cartridge cases, and the brass used for them. In order to do this, the inspector must have the right of access to any work and tests referring to the cartridge cases; he must have the right to enter any shop during any time of the day or night, where the manufacture of the cartridge cases ordered may take place, _i.e._, the casting and rolling of the brass, drawing, annealing, finishing, etc.

If the firm with whom the order for the cartridge cases is placed does not cast brass, but obtains it from other works, the inspector has the right to visit these latter works in order to ascertain the quality of the casting (and qualities of copper and zinc), method of cutting the top and bottom parts of castings, method of rolling, etc. The inspector’s expenses with reference to his journey to the brass works in such case must be borne by the firm with which the order for the cartridge cases has been placed. The minimum number of the necessary journeys must be determined before the placing of the order.

The firm, which is manufacturing the cartridge cases, must have a testing machine for the mechanical tests of the metal used for the cartridge cases; it must also possess a microphotographical laboratory for the brass (the power of the microscope must be at least 100). The firm must furnish the inspector with the results of all the chemical, microscopical, thermal, mechanical and any other tests carried out on the brass used for the manufacture of cartridge cases, as well as on cartridge cases themselves. In addition to this, the inspector must be given the right to use all the firm’s testing plant for the above-mentioned tests. The inspector must carry out the specified tests mentioned in the following for the acceptance of the cartridge cases.

Independently of the above, if the inspector thinks it necessary, for the purpose of ascertaining the qualities and evenness of the material used for the cartridge cases, as well as the cartridge cases themselves, to carry out in addition some other trials, the firm must provide him with all necessary assistance.

The firm must place at the sole disposal of the inspector sufficiently large dry and heated accommodations for carrying out his inspection, provided with cupboards for his gages; scales must also be provided; the place must be lighted by electricity, and all necessary power for the inspection must be provided; gages; and a microscope of from 40 to 50 power.

All gages used for the gaging of cartridge cases must be checked by the inspector before the beginning of the inspection, as well as during the inspection. Before submitting the cartridge cases manufactured to the inspector, the works must submit them to their own examiners. These examiners must work according to the rules given them by the works, and prepared in conjunction with the inspector. The firm must provide their examiners with a separate set of gages manufactured similarly to those supplied to the inspector.

The inspector has the right to inform the management of the works of all defects noticed by him in the manufacture of the cartridge cases, as well as of those defects which occur in the cartridge cases submitted for acceptance. Finally, he has the right to suggest some improvements in the manufacture of the cartridge cases; it is left to the discretion of the management of the works to make use of the above suggestions, if it is found advisable by them to do so, but the inspector has no right whatever to interfere with the orders issued by the management of the works.

=Clause 2. Test Consignment.=--Before beginning the manufacture of the order, the works must submit a test consignment. The cartridge cases for test consignment must be manufactured to the approved drawings, and made of brass according to these specifications. During the manufacture of the cartridge cases, it is required:

1. That the annealing of the cartridge cases shall be regulated to prevent any over-heating of the metal.

2. That after the cartridge case is properly formed, the upper half of the case shall be definitely annealed at a temperature not less than 400 degrees C.

3. That the mechanical quality of the metal in the manufactured cartridge case shall be in accordance with these specifications. The method of manufacturing the cartridge cases, as well as the regulation of the annealing before drawing, is left to the discretion of the works. The test consignment must be inspected and gaged by the inspector, and then sent for firing tests. The inspector must measure, on all cartridge cases in the test consignment, the diameter of the case near the bottom next to the flange, at a distance of ¹⁄₂ and 1¹⁄₂ inch from the flange.

After firing the first round, all cartridge cases must be inspected and measured on the same diameters on which they were measured before firing. The cartridge cases showing the maximum increase of diameter are to be resized after each round, together with those that are doubtful with regard to strength, if such re-sizing is allowed by these specifications. The cartridge cases spoiled during re-sizing must be replaced by new ones from the same consignment, but these new cases must be fired the same number of rounds as the old spoilt cases.

The consignment will be accepted:

1. If all cartridge cases after firing are extracted without any difficulty.

2. If no case shows longitudinal or transverse cracks (or any other cracks).

The cartridge cases which are supplied together with shell must be checked and examined in order to ascertain whether the shells are sufficiently secured in the case.

The test consignment of cartridges must be manufactured at the expense of the works, but the tests are carried out at the expense of the government.

In the case of an unsatisfactory test of the first consignment, the works have the right to submit a second test consignment. In the case of unsatisfactory results of the tests of the second consignment, the military administration has the right to cancel the contract.

The inspector has to weigh all cartridge cases of the test consignment, ascertaining thus the mean weight. In addition, the inspector must carry out the following test on the cartridge cases of the test consignment:

1. Chemical composition of brass.

2. Mechanical and microphotographical qualities of metal in the manufactured cartridge cases.

3. The temperature of the last annealing, _i.e._, the temperature of annealing before last drawing, temperature before compressing, and temperature of the final annealing of the finished cartridge case.

The temperatures of annealing must be ascertained by pyrometers. For this purpose such pyrometers as Ferry may be used, in which the temperature is ascertained by the color of the object heated.

The methods of manufacture of the order of cartridge cases must be similar to those used for the manufacture of test consignment. In case of any alterations in the method of manufacture, the works must inform the inspector to that effect, and he must report the matter to the military administration with his opinion on the value of such alteration in manufacture. It is left to the discretion of the military administration to allow such alteration or to demand from the works the delivery of a new test consignment. A firm which has already manufactured cartridge cases of certain type may be released from the delivery of a test consignment, provided the methods of manufacture have not been altered.

=Clause 3. The Acceptance of the Brass.=--The brass used in the manufacture of cartridge cases must be of the following composition:

Copper from 67 to 72 per cent.
Zinc from 33 to 28 per cent.

The proportion of other metals must not exceed 0.5 per cent, except tin, which must not exceed 0.3 per cent.

During the manufacture of cartridge cases in the same consignment, the variation of copper in the brass must not exceed + 1 per cent, or - 0.5 per cent compared with the usual composition used by the works which composition must be given to the inspector before the manufacture of the test consignment. The method of manufacture of brass is left to the discretion of the works. The only requirements are as follows:

1. The cast ingots must be annealed before first rolling.

2. All rolling must be carried out in the same direction, thus allowing the top end of the casting always to be distinguishable.

The top or bottom portion of the castings must not be used for the manufacture of cartridge cases. They must be cut from the ingots by the works manufacturing the brass, or the blanks for the cartridge cases must be cut at a certain distance from both ends of the ingots. On receipt of the brass ingots, the works manufacturing the cartridge cases must inform the inspector to that effect, giving him the chemical analysis and the composition of the casting. The consignment of the brass must be sufficient for the manufacture from it of the whole consignment of the cartridge cases. At the works which manufacture the brass, test bars must be cast from the same furnace and from material of the same quality, melted in a similar manner, and stamped with the same number as the castings. This number must be stamped at the bottom of the cartridge case.

The brass used for tests must be submitted to the inspector in bars, and the cutting of the test disks from the bars must be carried out under the inspector’s supervision. A few bars are to be used for the microscopical analysis. The bars of each consignment must be stamped with a number, which number must be stamped afterwards on the blanks during all the drawings. This number must also be stamped on the bottom of the case, as mentioned. These numbers must be put by the inspector in the report together with chemical analysis of metal, composition of casting, number of rods delivered, time of delivery, name of brass foundry by which the brass has been supplied (if the manufacturers do not manufacture brass themselves), and the number of test disks cut. For each consignment of cartridge cases manufactured from brass bearing a certain number, at least one chemical analysis must be made. The brass not answering to the requirements of the chemical analysis will be returned to the manufacturer for re-casting.

To insure that the amount cut off from the top and bottom of the rods is sufficient, the inspector must ascertain from the first consignment the number of cartridges manufactured, with defects inside as well as outside, from (1) disks cut from upper end of rod, (2) disks cut from roller end of rod, and (3) disks cut from the remaining part of rod. The percentage of cartridge cases with defects, in the above-mentioned three groups, must not differ materially from each other. The above-mentioned tests must be carried out from time to time during the manufacture of the cartridge cases.

The following methods can be used to ascertain that the ends of any rod are cut off sufficiently:

1. At the center of the rod, cut a piece from the top of the upper blank; the transverse surface of the piece must be polished and etched with a weak solution of nitric acid; if the piece cut off from the top end was not sufficient, the test piece will show, in the middle, more or less solid black lines, inside of which, under the microscope, it will be possible to see small microscopical flaws and foreign substances.

2. The transverse test piece cut in the above-mentioned manner must be broken in a testing machine; if the top portion was not sufficiently cut off, the middle of the piece will show ruptures in the metal.

=Clause 4. The Arrangement of the Cartridge Cases in Lots.=--The cartridge cases for delivery must be arranged in lots. It is desirable that the cartridge cases in each lot should be manufactured from one casting of brass metal. If the lots are compiled from the cartridge cases of different castings, it will be necessary to select cartridge cases for the control test from all the castings, and the cases left over from the lots already tested and accepted may be placed in the new lots without repeated tests.

The dimensions of punch and die for the last drawing must be verified from time to time. The control of the annealing must be carried out by means of a pyrometer. The cartridge cases in each lot must be inspected as follows: 1. Outside inspection. 2. Inspection of dimensions and weight. 3. Mechanical test of the metal. 4. Firing test.

=Clause 5. Outside Inspection.=--The cartridge cases, before submission for inspection, must be cleaned inside and outside with sawdust and sand, or with brushes. The following defects usually occur in the cases.

1. _Cracks._ Longitudinal cracks chiefly occur at a distance of two or three inches from the flange, and, generally speaking, form two parallel lines very slightly noticeable on the inner surface. Transversal cracks, slightly noticeable, generally occur above the flange at the bottom; they are always on the outside surface and very seldom penetrate through. Cases with such defects must be rejected.

2. _Ruptures._ These defects usually are on the outer or inner surface of the cases and show that something is wrong with the metal; cartridge cases with ruptures are rejected without further consideration. Slight ruptures found in the corner of the socket for the primer do not affect the strength of the case and are, therefore, allowed.

3. _Flaws and Fissures._ Cases submitted to the inspector after being filed and cleaned on the inner surface are rejected. Cases with flaws and fissures on the inside surface must be submitted to the inspector separately from the others and the filing of them must be carried out under the inspector’s supervision. The inspector has to determine to what extent the flaws are vital. Special attention must be paid to the flaws on the rim and on the tapered portion.

4. _Scratches._ These are usually due to the punch, or to dirt which may have been in the punch. Small scratches do not vitally affect the strength of the cases. Cases with deep scratches are rejected, especially if on the inner side of the case a very noticeable mark is seen, extending to the lower part of the case.

5. _Scars._ Small scars which make the surface of the case dull are allowed. Large scars on the surface giving the appearance of a grained surface indicate too high a temperature in annealing, and cases with such scars must be rejected.

6. _Dents._ Dents, if rectified, are allowed on cases if they are not important; they are not allowed on the conical portion or at the end of the case.

7. _Goffering._ Goffering on the inner surface of the case is usually due to the uneven drawing of the metal in the case of very rigid material; it is due to defects in the uniformity of the material. Goffering does not appreciably affect the strength of the cases, and therefore cannot generally be taken as a reason for rejection. A large amount of goffered cases shows that there are some abnormal conditions in the manufacturing of the brass or the cases themselves. In such cases the inspector must point this out to the works, and if the works will not take measures to remove these defects the goffered cases must be rejected.

8. _Folds._ Folds of metal are sometimes noticed inside the case at the bottom and show bad manufacture. Cases with such defects are rejected.

9. _Other Small Defects._ Dents at the bottom, inside, and other small defects are allowed at the discretion of the inspector.

=Clause 6. Gaging.=--Cases which pass satisfactory outside inspection must be gaged by means of gages for maximum and minimum allowances. The dimensions gaged are as follows:

1. All outside diameters of the cases must be gaged with ring gages or half ring gages.

2. The inner diameter of the end of the case is gaged with calipers.

3. All outside dimensions of the bottom of the case are gaged as follows:

(a) Diameters of flanges by half ring gages.

(b) Thickness of flanges with snap gages.

(c) Concentricity of the bottom of the case by ring gage.

4. The thickness of the bottom by special gage.

5. Concentricity of the hole for the primer, by special gage.

6. All dimensions of the hole for the primer must be gaged with a set of corresponding gages.

7. The flatness of the surface, the absence of cuts and hammering of the metal around the hole for the primer with a straightedge.

8. The outline and the length by a special gage.

9. The thickness of the walls is gaged by means of a snap gage with cut corresponding to the thickness of the cartridge case at the end, by a small special gage with pointer for ascertaining the thickness of the walls as well as the depth of the cleaning away in places near the end of the case, and by a special gage with pointer for ascertaining the thickness of the walls along the whole length of the case.

For the purpose of ascertaining that the outline of the cases is correct, the inspector has the right to select 0.2 per cent of the cases from the lot, choosing preferably from the rejected cases; special attention must be paid to the difference in thickness of the walls at the lower end of the cases. To ascertain the similarity in weight, all cases must be weighed; the difference from mean weight must not exceed the limits fixed for each caliber of the cases.

If during the preliminary examination of the cases more than 15 per cent are found defective, as regards the metal or dimensions, the inspector has the right to stop the further examination of the cases submitted, and to ask the firm to re-submit them again. If, after re-submitting, and during the second examination of the cases, more than 5 per cent are found unsatisfactory, the whole lot will be rejected.

=Clause 7. Mechanical Tests.=--In the following paragraphs are given special conditions for the acceptance of cartridge cases for the guns of different calibers. As a general rule, the mechanical qualities of the metal used for cartridge cases must comply with the following conditions:

1. The rigidity of the bottom and the lower end of the cases must be sufficient to insure the proper extraction of the cases.

2. The rigidity of the end of the cartridge must insure the proper grip of the shell, and for the howitzer cases must not show any dents on the metal.

3. The rigidity of the metal along the whole length of the case must change evenly, without sudden changes.

During the manufacture of the cases, care should be taken to work the metal as near as possible to the lower limits of the rigidity of the metal, as any extra rigidity affects the strength of the case during firing and in storage.

The mechanical qualities of the cases must, as far as possible, be alike; they are tested (a) by a breaking test of the metal used for the cases; (b) by ascertaining that the shell is fixed properly in the case (a casting may be used for this purpose manufactured to the dimensions and the weight of the proper shell); (c) microscopical analysis of the metal; and (d) any other methods at the discretion of the inspector, as, for instance, by ascertaining the hardness of the metal, compression of the mouth of the case, etc.

For the tensile test the inspector selects from each lot about five cases rejected on account of the dimensions; these are cut in halves for the purpose of ascertaining the thickness of the walls. The number of cases used for mechanical tests may be increased by the inspector if it is required by the quality of the material. From each case selected for the mechanical test, three rings must be cut, one inch wide; one next to the flange, 1¹⁄₂ inch above it; one from the middle of the mouth; and one immediately under the conical portion, if such portion exists; otherwise from the middle of the case. The rings cut in the above manner must be cut longitudinally and straightened by delicate hammering with a wooden mallet or by rolling between wooden rollers. From each strip obtained in such manner two test pieces must be cut with a distance between marks of 1.97 inch (50 millimeters). The width of the test pieces must be the same. Ten division marks must be made on the test pieces, each division being 0.197 inch (5 millimeters). During the mechanical test, the following data must be ascertained: Breaking stress, total elongation, and local elongation between all division marks.

=Clause 8. Firing Proof.=--After the examination of the whole consignment, the inspector selects some cases for proof by firing. The inspector chooses for the firing trials those cases which he considers the least satisfactory. The works have the right to re-examine the cases selected by the inspector for firing, and remove any case selected by the inspector; but, in such an instance, all cases with similar defects are to be rejected, and the inspector replaces the cases removed by the firm. The works have not the right to remove the cases selected in the above manner more than twice for each consignment. The firing proof of the cases must be carried out at any place selected by the artillery administration, where the cases must be delivered by the works.

The firing proof must be carried out in a similar manner to the test consignment, and the submitted consignment is accepted:

1. If all cartridge cases after firing are extracted without any difficulty.

2. If no case shows longitudinal, transversal or any other cracks, or ruptures of metal.

If during the firing trials one case shows a crack or is difficult to extract, the works have the right to review the consignment and submit for the firing trials a second set chosen by the inspector. In such instances, the works have no right to remove any case selected by the inspector for secondary proof; the number of cases selected for secondary proof as well as the number of proof rounds fired may be increased. For the acceptance of the consignment, all cases must give satisfactory results in the second firing test. If the two consecutive firing proofs will give unsatisfactory results, the artillery administration has the right to cancel the contract. The firing proof is carried out at the expense of the government, and the cases normally used are counted as part of the consignment. The fired cases, after re-sizing, annealing and inspection, are submitted by the works to the inspector, and afterwards they must be packed in separate boxes.

The cases required for secondary proof must be at the expense of the manufacturer.

=Clause 9. Varnishing.=--In case of satisfactory results of firing proof, the works varnish the cases inside as well as outside. The varnish must be used evenly. When scratched with a wooden point or with the finger nail, the varnished surface must not show any impression; when scratched with a metallic point the varnish must not crumple, and must not show any cross cracks. The varnish on the cases must not alter its appearance if placed for twenty-four hours in water, and after removal from the water and again dry, it must adhere so firmly as not to be removable under pressure of the finger.

The specific gravity of the varnish must be from 0.9 to 0.94. Brass strips covered with the varnish must not show any oxidizing action. After the heating of the varnished strips during 24 hours in the water bath at a temperature of 167 degrees F., the varnish, when heated, must not peel off. For the purpose of ascertaining the character of the reaction of the varnish, 10 cubic centimeters (0.61 cubic inches) of solvent must be distilled from 100 cubic centimeters (6.1 cubic inches) of the varnish, and the solvent obtained in this manner, when mixed with a weak solution of litmus, must not give an acid reaction.

=Clause 10. Stamping.=--The cases must be stamped as follows: On the top, the number of the consignment of brass; at the left, number of the consignment of the cases and the year of manufacture; on the right, the firm’s initials; at the bottom, the inspector’s stamp, which must be placed after the inspection, and the stamp which means accepted and which must be placed after the firing proof. The letters and figures must not exceed ¹⁄₈ inch in height.

=Clause 11. Packing.=--The cases, after being wrapped in paper, are covered with straw caps and packed in strong wooden boxes. These must be dovetailed from pine or fir wood, with rope handles and iron bands. The lids must be fixed with screws. The works have to pack the cases to the satisfaction of the inspector. To ascertain the accuracy of packing, the inspector turns over one of the boxes chosen, and after that the case must not show any dents or any noticeable damage to the varnish on the cases. Fifty cases are packed in each box.

The boxes must have the following marking:

Accepted Cases:

Caliber of Cases
Name of Works
Year of Manufacture
Number of Cases in Lot
Number of Consignment

Fired Cases:

Caliber of Cases
Name of Works
Year of Manufacture
Number of Cases in Lot Fired, but Good for Use
Number of Consignment

=Condition for Acceptance of Cartridge Cases for 3-inch Field Guns.=--The test consignment must consist of fifty cartridge cases. The proof must be carried out from the gun with pressure of about 15.75 tons per square inch (2400 atmospheres). Ten cases are selected from those showing the maximum increase of diameter and are used for re-charging; they must be re-annealed after each round; all doubtful cases must be added to the above-mentioned cases. Each of these cases must stand eight rounds.

The gaging must be carried out as follows:

Dimensions in Inches
Normal Reject

1. Diameter of the case near bottom, gaged with
half ring gages 3.294 3.286

2. Diameter of flange, gaged with half ring gages 3.547 3.539

3. The outside diameter of the end, gaged with
half ring gages, and with gage inserted in
the case 3.004 3.000

4. The inner diameter of the case 2.923 2.927

5. The thickness of the flange 0.142 0.134

6. The thickness of the bottom, gaged with
special gage 0.157 + 0.030
- 0.010

7. The concentricity of the hole for the primer must be gaged with
special gage.

8. The concentricity of the flange with reference to the body must be
gaged with half ring gage, the dimensions of which must be as follows:

(a) Maximum diameter of flange.

(b) Maximum diameter of the case at bottom.

(c) Maximum thickness of the flange.

9. The outline and the length of the case must be checked by special
chamber gage. The allowance for length must be ± 0.010 inch.

10. The gaging of the hole for the primer is carried out by the
following gages:

(a) Screw gages, normal and reject.

(b) Normal gage which is used for the gaging of the whole diameter
and the depth of the hole for the primer, normal and reject.

(c) Reject gage for the flange of the primer.

(d) Reject gage for the thread.

(e) Reject gage for the plain surface of the hole.

(f) Normal and reject gages for the thickness of the hole for the
flange of the primer.

(g) Normal and reject gage for the depth of the plain portion of
the hole.

(h) Gage for the ignition hole.

11. Normal and reject gage for the height of the boss for the primer.

12. Gages, compasses and special gages for the thickness of the
walls and for the depth of filing of the inner as well as the outer
surfaces.

13. Straightedge for gaging the bottom surface of the case.

The difference in the weight of cases from mean weight must not exceed ± 3 ounces.

The test pieces subjected to the tensile test must show the following breaking stress:

(a) At the ends, 48,000 to 57,000 pounds per square inch, with local elongation not less than 60 per cent.

(b) Next to the flange, from 64,000 to 85,000 pounds per square inch.

(c) Next to the conical portion, not less than 52,500 pounds per square inch.

=Firing Trial.=--For the firing trials, thirty cartridge cases must be selected. These cases must be measured and must pass a similar test to that of the test consignment, with the following exceptions.

1. Only five cases are taken for re-proving, including cases showing the maximum expansion, and those doubtful with reference to their strength.

2. The cases are to be fired five times.

During the firing of the secondary proofs, as well as during the firing of the cases selected from the lots entirely consisting of the defective cases, the number of cases as well as the number of re-tests may be increased to the number fixed for the test consignment.

=Specifications for Primers.=--The charge primer consists of brass body, detonator, bush, brass anvil, a charge of gun powder (not polished with graphite), a disk of saltpeter-soaked tissue paper, four powder cakes, disk of saltpeter-soaked muslin, disk of parchment, and a brass disk bored in the center and coated outside with thick shellac varnish mixed with cinnabar.

=Detonator.=--The detonator consists of a small copper cap containing a charge of 0.275 grain of the detonator composition, covered by a thin paper parchment disk and compressed with a pressure of 125 pounds. The thickness of the parchment is between 0.002 and 0.0025 inch. The surface of the parchment facing the composition is coated by a thin layer of fluid shellac varnish composed as follows: 15.12 gallons of 95 per cent alcohol and 20 pounds of shellac.

The detonator composition contains 50 per cent fulminate of mercury, 20 per cent chlorate of potassium and 30 per cent glass ground to dust and sifted through a sieve No. 100 (100 meshes to 1 inch). To this mixture is added 0.25 per cent of tragacanth gum and a trace of gum arabic. The composition is placed in the cap while moist. After compression the detonator is dried for ten days at a temperature of 88 degrees F., and twenty days at 111 degrees F. Then the exterior surface of the parchment disks is coated with a thick varnish composed of 0.891 gallon of 95 per cent alcohol, 2.75 pounds of shellac, and 0.5 pound of resin. The varnished detonators are dried at room temperature for five or six days, and then undergo a final examination, in which the defective caps will be rejected. The caps, when ready, must have even wedges, no rents, cracks, dents or such like defects, and the parchment disks must be placed concentric with the edges of the caps.

Out of a lot representing a day’s output (about from 10,000 to 15,000) of detonators, twenty-five are set aside without selection, for testing under a drop weight of 13.65 ounces, falling from a height of 3.94 inches. These must not show a single failure. If a day’s output of detonators does not answer that condition, it undergoes, after a supplementary drying, a second test in double quantity. Any lot of detonators that does not stand this test will be rejected and burnt out.

The tissue paper and muslin disks are soaked with a 10 per cent solution of saltpeter. The powder cakes are compressed gun powder, not polished with graphite, and have a diameter of 0.748 inch, a height of about 0.120 inch, and weigh from 21.95 to 23.32 grains each.

=Charging Primers.=--The charging of primers is preceded by the examination of their bodies and other parts. The charging is done in the following order: The detonator is placed in the bush which is screwed onto the end into its seat and then nipped in two places in order to prevent its becoming unscrewed. The anvil is then screwed into its seat, so as to press tightly on the detonator composition, without, however, cutting the parchment disk. To inspect the proper screwing in of the anvils, 30 primers are set aside out of every 300, and from those the anvils are screwed out and the detonators examined. The parchment disks must bear clear marks of the anvils, without being cut through.

In properly fitted primers the anvils are prevented from becoming unscrewed by nipping them in two places. A charge of from 10.286 to 10.972 grains of powder is placed in the groove between the hose and the internal surface of the body of the primer. This charge must fill the groove to the brim. The powder is now covered with the disk of tissue paper soaked in saltpeter. On the top of it will be placed four powder cakes, which will be covered first with a disk of saltpeter-soaked muslin, then with a parchment disk and lastly with a brass disk bored in the center, after which the upper edge of the primer is closed in, this operation being carried out in three stages. After the first pressing, a proper position is given to the disks inside the primer; after the third (final) pressing the primer is to be gaged. The upper side of the brass and parchment disks is varnished with thick shellac mixed with cinnabar.

After having been dried in the shop for 24 hours, the primers are packed in cardboard boxes. Two such boxes, (50 primers in each) are sealed hermetically in zinc boxes. The proper hermetic soldering of some boxes chosen at random will be tested. Eight zinc boxes are packed in one wooden box, which will thus contain 400 primers.

=Inspection of Primers.=--Bodies and other details will be manufactured of brass, the composition of which will be left to the discretion of the works, but on the express condition that the primers will comply with all requirements stipulated. The best results have been obtained when the metal contained from 67 to 74 per cent of copper, and from 33 to 26 per cent of zinc.

Before beginning the manufacture of the order, the works with which the order will be placed must deliver a test consignment consisting of 100 primers. The test consignment of primers after being charged must be subjected to a firing trial. The conditions of this trial are similar to those used for the trials of the complete order. The order must be submitted in lots of 25,000 each.

The gaging of dimensions at the works manufacturing the primers must be carried out after each separate operation of manufacture, for which approved gages and control gages must be used. All the gages must be manufactured by the works, with which the order for the primers is placed, with the exception of the gage nut used for the gaging of the outer thread and the check screw for same. The last mentioned gages must be handed over to the primer works by the proper authorities.

The primers, before being charged, will be assembled at the works which manufacture them, _i.e._, bushes and anvils are screwed in, and the primers are delivered to the explosive works in such condition. After the completion of the manufacture of a lot of 25,000 primers, 1000 of them, chosen at random during the manufacture, will be sent to the explosive works for inspection, for testing the rigidity of the metal, and for preliminary tests of the metal by firing.

If, during the trial for the rigidity of the metal carried out by the compression of 50 primers chosen at random, more than 5 per cent show ruptures, the complete lot of 1000 primers will be returned to the manufacturers.

In the case of satisfactory results of firing trials, the remaining 24,000 primers will be delivered to the works intrusted with the charging.

If, after partial examination of a lot (not less than 1000 primers), more than 10 per cent of primers will be rejected in accordance with the following two paragraphs, the further inspection will be stopped at the charging works, and the whole lot will be returned for resorting.

When inspecting primers, the following defects are not allowed: ruptures, blow-holes, fissures, flaws, sandy surface, dirt, oil, dust, shavings, dents on the bottom surface of the flange, dents at the bottom of the charge chamber, and considerable crumbling of threads (more than one-fourth of a thread). The examination of the bottom surface for evenness must be carried out by spinning the primers on a polished steel plate. The primers which will not spin must be rejected.

The primer chambers must be varnished. The anvils must not show any flaws and fissures at their striking edge and at the threads. The striking edge must not be sharp, to prevent the cutting through of the parchment disks of the detonator; generally speaking, the anvil and the bush must also answer all the requirements of the preceding paragraph.

=Gaging.=--One hundred primers complete from each lot must be gaged. Special attention must be paid to the following points:

(a) All primers to be screwed into gage without being specially loose.

(b) The thickness and the outer diameter of the primer head must not exceed the specified maximum dimensions, thus securing the proper fit of the primer flange in its seat in the cartridge case.

(c) The height of the boss inside the primer must be strictly in accordance with the allowance given.

(d) The inner thread of the boss must be strictly in accordance with the gage.

(e) The seat for the detonator and the hole in the bush must be correct and in accordance with the gage.

(f) The thickness of the bottom of primer (0.067 to 0.077 inch) must be in accordance with the gage.

The anvils and bushes must screw and unscrew easily, without being loose and must be interchangeable. After charging, all primers will be inspected with regard to their height, and gaged outside. In case of unsatisfactory results in gaging (rejected primers exceeding 3 per cent) an additional 100 primers must be chosen for the same purpose, and in case the results are the same, the whole lot will be returned to the works manufacturing the primers for resorting.

=Firing Trials.=--Fifty primers out of 1000 delivered from a lot of 25,000, after being charged, are tested with reference to the quality of the metal, by firing with increased charge at a pressure of 2400 atmospheres (15.75 tons per square inch). These primers, after the test, should not show any breakage (after being unscrewed) through cracks and flaws, the presence of which would mean that the gas escaped through the base of the primers. The escape of gases leaving a residue between the side surfaces of the primer flanges and their seating is allowed on not more than 30 per cent of the primers subjected to firing test from new cartridge cases; in the case of using fired cartridge cases, no attention must be paid to the presence of the above-mentioned residue.

Non-through cracks are allowed on not more than 2 per cent of tested primers; in the case of a larger percentage, but not exceeding 4 per cent, the whole lot must be resorted and retested. The recurrence of 2 per cent of non-through cracks in the second test may not be taken as a reason for the rejection of the whole lot; 50 primers must be used for the second test. In the case of the absence of above-mentioned defects, only those primers will be considered satisfactory which, after firing, can be removed from the cartridge case by hand or by an ordinary spanner.

The serviceableness of the primers is determined by firing 50 primers chosen at random from the complete lot of 25,000 charged primers. The conditions just laid down hold good for this trial also. In addition to this, no complete misfire must occur; not more than two primers may misfire once each, with lock in proper order. (Before firing, the tension of the main spring and the protrusion of the firing pin must be verified.) A second test may be carried out if during the preliminary test defects occur. The second test must be carried out on double the number of primers taken at random, _i.e._, on 100 primers. During second test the same conditions as laid down for the first test hold good. Primers passing successfully the first or second firing tests are accepted for the service. A lot of charged rejected primers must be destroyed and the metal scrapped.

In addition to the firing tests, the following test must be carried out by the works intrusted with the charging of primers to determine the correctness of charging: 1. One per cent of a day’s output must be tested under a drop weight of five pounds falling from a height of 0.39 inch with flat firing pin 0.25 inch in diameter; during this test no primer must detonate. Primers having passed this test and not showing any noticeable mark on the base must be recharged and added to the lot. 2. When testing 0.5 per cent of each day’s output under a drop weight of five pounds, falling from a height of 5.9 inches, with firing pin of an approved pattern, no primer must fail to explode.