Chapter X: Specifications for British 18-Pounder Quick-Firing Shrapnel Shell

The following paragraphs, abstracted from the official specifications, give all the information contained in these specifications relating to the manufacture and inspection of the British 18-pounder, quick-firing shrapnel shell.

=Body.=--The body of the shell is made of cast or forged steel of the best quality for the purpose, turned or ground to the form and dimensions, and having the edge of the base rounded. If made of cast steel, the casting must be clean, of uniform transverse thickness, free from flaws, blow-holes, and other defects. The use of chaplets is prohibited. If made of forged steel, the body must be forged hollow, and free from forging marks and flaws. Should the shells be subjected to heat-treatment, this must be carried out in batches consisting of shells of the same cast. An undercut groove, with two projecting waved ribs, will be turned on the body. Three chisel cuts may be made across the waved ribs in the groove for the driving band, at an angle to the longitudinal axis of the projectile to allow the air in the channels between the ribs to escape when the band is being pressed on. The top is threaded to receive the socket, and a groove for the fuse cover provided. The steel body alone must weigh 6 pounds 5 ounces 12 drams, plus or minus 2 ounces.

=Driving Band.=--The driving band is made from a ring of drawn or electro-deposited copper, pressed into, and in contact with, the bottom and undercut of the groove in the shell all around, and accurately turned to the form required. The weight must be 4 ounces 12 drams, plus or minus 2 ounces.

=Socket.=--The socket is made of composition metal, known as Class “C,” threaded externally below the shoulder to fit the body, and internally to receive the fuse, the bottom being bored to receive the top of the central tube. The junction of the socket and central tube is soldered to prevent the resin getting into the tube and socket. A hole is to be bored in the side, threaded and fitted with a steel fixing screw. The weight must be 8 ounces 8 drams.

=Central Tube.=--The central tube may be made of brass, copper, delta metal, or gun metal. The lower end is to have a shoulder to rest on, and to be threaded to enter the steel disk, the bottom being reduced in diameter to fit the neck of the cup. Weight, 2 ounces 12 drams.

=Steel Disk.=--A steel disk, of the form shown in Fig. 2, will rest on the shoulder in the bottom of the body, a hole being bored and threaded through the center of the disk to receive the central tube. Weight, 9 ounces 8 drams.

=Tin Cup.=--The cup in the base of the shell to contain the bursting charge will be made of tinned plate to the form and dimensions shown in Fig. 2, the parts being soldered together. Weight, 1 ounce 12 drams.

=Gages.=--Contractors may send their gages at any time to the chief inspector, Woolwich Arsenal, London, England, to be checked and compared with the standard gages.

=Screw Threads.=--The screw threads must, unless otherwise stated, be of the British standard fine screw thread, and conform to the chief inspector’s standard gages.

=Preliminary Examination of Contractor’s Work.=--The bodies, after completion of machining, will be submitted at the contractor’s works, to an inspector, for preliminary examination. Bodies made of cast steel must also be submitted for a hydraulic test under a pressure of 100 pounds per square inch. Any shell which shows the slightest leak, or fails to satisfy the conditions, will be rejected.

=Assembling.=--The tin cup, steel disk, and central tube are to be placed in position and the shell filled with mixed metal bullets, 41 per pound (composed of seven parts of lead and one of antimony), the interstices between the bullets being filled with resin, which must be perfectly pure, and filtered when in a liquid state through a sieve having 32 meshes per inch. The socket is then screwed onto the body as tightly as possible, the threads having been previously coated with Pettman’s cement or red lead.

=Marking and Plugs.=--The shells are to be marked on the side, above the driving band. Plugs for the protection of the fuse holes in transit will be supplied, free of charge, on demand, by the ordnance officer to whom delivery is to be made.

=Delivery.=--(a). The shells will be covered with a thin coating of vaseline or other similar anti-corrosive grease, which must be of such a nature as not to interfere with the gaging, and they will then be delivered unpainted, for inspection and proof. The shells must be perfectly cleaned out, empty, complete in every respect, and dry internally. (b). Such marking as may be necessary to identify the steelmaker’s cast number, and, in case of heat-treatment, the batch number, must be maintained by the contractor upon every shell throughout manufacture. (c). The shell must be delivered in lots for purposes of proof. A lot for this purpose will consist, as far as possible, of shells of the same cast, and, when heat-treatment is employed, of shells of the same batch number, and must not contain more than 121 shells. (d). When the number of shells in a cast or batch is less than 100, two casts or batches may be grouped together for this purpose.

=Main Examination after Delivery.=--(a). Any shell of a lot which fails to pass the chief inspector’s gages, or fails to satisfy the chief inspector of its serviceability, will be rejected. (b). If at any time during the examination it is found that defects of any nature, other than errors of machining, which involve rejection of defective shells, amount to 5 per cent of the number of the shells in the lot, the “lot” will be rejected, (c). One or more shells selected from the lot will be taken to pieces, and the body broken, if necessary, to ascertain that the details of manufacture and component parts are correct, and that the material is sound. Should they be incorrect, or the material unsound, in any particular, the lot will be rejected. The driving band will be cut out, and should it appear not to have been pressed thoroughly home into the undercut and groove throughout, the lot will be rejected. (d). If, at any time during the examination of a lot, it is found that 5 per cent of the shells in the lot depart from the approved design, further examination of the lot will be suspended. The whole of the lot must be re-examined by the firm and those shells which are incorrect eliminated. Those shells in which the departure can be rectified may be brought to the approved design by the firm. The lot may then be re-submitted.

=Tests.=--At least 1 per cent of the shells of every cast will be subjected to tensile tests. Test pieces will be cut from the shell blank, or from the finished shell at the option of the chief inspector, and must be capable of standing the following minimum tests:

+-------------------+-------------------------------------+
|Tenacity, Tons per | Elongation in a Test Piece 2 Inches |
| Square Inch | in Length, or such Piece as can be |
+ -------+----------+ cut from the Shell, provided that |
| Yield | Breaking | |
| Point | Stress | Length / √Area = 4 |
+--------+----------+-------------------------------------+
| 36 | 56 | 8 per cent |
+--------+----------+-------------------------------------+

If any one or more of the conditions in this clause are not complied with, the lot, or lots, of shell affected, will be rejected, and must not be re-submitted. The contractor will supply, free of charge, the necessary “Class C” metal for testing, if requested by the chief inspector to do so. The pieces should not be less than 7 inches in length, nor less than 1 inch in diameter, and will be required to stand the following test:

+-------------------+-------------------------------------+
|Tenacity, Tons per | |
| Square Inch | |
+--------+----------+ Elongation in a Test Piece 2 Inches |
|Yield | Breaking | long and 0.564 Inch in Diameter |
|Point | Stress | |
+--------+----------+-------------------------------------+
| 6 | 12 | 10 per cent |
+--------+----------+-------------------------------------+

=Proof.=--(a). A percentage of the shell will be fired for recovery from an 18-pounder Q. F. gun, with such a charge as will give a chamber pressure not less than 15 tons per square inch. Should the shell so fired set up above the high diameter of body, or break up in the gun, or should any portion of the driving band separate from the shell before first graze or impact, or should the recovered shell show that the shock of discharge had distorted the disk supporting the bullets, or cause such alteration of the internal parts as would interfere with the correct action of the shell, or should any of the components be incorrect, the lot will be rejected, provided always that the pressure did not exceed the specification proof pressure by 0.5 ton. If the pressure did exceed this limit, a second proof must be taken at the government’s expense before the lot is rejected. The pressure of the round, if not taken, will be assumed to be that of the last round fired with the same charge in which pressure was taken. Further, should the shell be reported unsteady in flight, and be found on recovery to be without its driving band, or with the driving band loose or slipped in its seating, then the driving band of a similar number of shells to that taken for firing proof may be cut out to ascertain whether they have been properly pressed on; if they have not been pressed down to the satisfaction of the chief inspector, the lot will be rejected. If found correct, such shells will be rebanded by the contractor free of charge.

(b). The shells fired for proof may, after recovery, be broken to ascertain the soundness of their material. Should any of the material be unsound in any respect, the lot will be rejected.

=Re-submission.=--(a). A rejected lot must not be re-submitted unless the rejection is due to failure of the driving band, or to rectifiable gaging defects. (b). Shells put out at any period of inspection for remediable defects may be re-submitted for further examination after the defects have been rectified. It is to be understood that the examination of such shells at that time will be incomplete, and that they are liable to rejection after rectification. (c). If the contractor wishes to re-invoice a lot rejected for failure of driving bands, he must remove the shells and re-band them before they are again submitted, (d). Rejected shells will, if considered necessary, be marked with a small rejection mark, so that they can be readily identified if redelivered.

=Replacement of Proof.=--The contractor will be required to replace, free of charge, all shells expended in proof and examination, which, whether fired or otherwise tested, will be the property of the government.

=Packing.=--All packages are to be so marked that the goods contained therein may be readily identified with the invoice. Unless it is specified in the contract that the packing cases or other packing material are to become the property of the war department, they will remain the property of the contractor, who is responsible for their removal.

Should they not be removed within two months of the acceptance at the stores, they will be disposed of, and under such circumstances the contractor will not be entitled to make any claim for compensation. The packing cases must be marked “Returnable” or “Non-returnable.”

=Inspection.=--The shells may be inspected at any time during manufacture by, and after delivery will be subject to testing by, and to the final approval of, the chief inspector, Royal Arsenal, Woolwich, England, or an officer deputed by him. In cases of defects occurring in manufacture which necessitate repairs, the contractor shall bring the same to the notice of the inspecting officer, and shall obtain from him written authority to proceed with such repairs as may entail patching, burning, electric welding, or other similar processes.

WEIGHT OF 18-POUNDER SHRAPNEL SHELL PARTS

Weights (avoirdupois)
Part Pounds Ounces Drams
Steel body 6 5 12 }
Driving band 4 12 } ± 2 oz.
Metal socket 8 8
Steel disk 9 8
Brass tube 2 12
Tin cup 1 12
Bullets, about 327 of alloyed metal,
41 per pound 7 14 13¹⁄₂
Resin 13 11
Total weight empty (unpainted)* 16 13 8¹⁄₂ ± 11 drams
Bursting charge 2 8
Paint 5¹⁄₂
Fuse 1 7 10
--------------------------------
Total weight 18 8 ± 5 drams

* To regulate weight of shell, a few buckshot may be used.

=Plug for Fuse Hole.=--The plug is to be made of a copper alloy, and to the form and dimensions shown on the drawing, threaded externally on the body, and a square recess, tapered, is to be formed in the top. The screw threads must, unless otherwise stated, be of the British standard fine screw thread, and conform to the standard gages of the chief inspector, Royal Arsenal, Woolwich, England. Contractors may send their screw gages to the chief inspector, to be compared with the standard gages.

Any plug of a delivery which fails to pass the inspecting officers’ gages, or shows flaws or sponginess on the surface, or fails to satisfy the chief inspector, Woolwich, as to its serviceability, will be rejected. If at any time during the examination it is found that defects of any nature, other than errors of machining, which involve rejection of the defective plugs, amount to 5 per cent of the number of plugs in the delivery, the whole order will be rejected. If at any time during the examination of a delivery it is found that 5 per cent of the plugs in the delivery will depart from the approved design, further examination of the plugs will be suspended; the whole of the delivery must be re-examined by the firm, and those plugs which are incorrect to design eliminated. Those plugs in which the departure can be rectified may be brought to the approved design by the firm. The delivery may then be re-submitted for examination. The contractor will be required to replace free of charge all plugs expended in test and examination, which will become the property of the government.