SPECIFICATIONS FOR BRITISH 18-POUNDER QUICK-FIRING CARTRIDGE CASE AND
PRIMER
The following specifications of the British 18-pounder quick-firing
cartridge case and primer govern the manufacture and inspection
of these cases and primers. They are abstracted from the official
specifications and give the most important information required by the
manufacturer and inspector.
=Construction.=--The cartridge may be either solid drawn brass or built
up, the nature of the alloy and the thickness and distribution of the
metal being left to the contractor, except that the dimensions must
agree with those in Fig. 1. The maximum weight is to be 3 pounds 1
ounce. If electrolytic copper is used, it must be melted and run into
ingots before use. In manufacture the number of drawings and the number
of annealings must not be less than six. Should any folds or rings
exist in the metal of the base, they must not be removed; any marks of
cutting or turning of the metal of the inside of the base will cause
the rejection of the cartridge. In the center of the base a hole is to
be bored and threaded to receive the primer. The cartridges are to be
marked on the base with the numeral and the contractor’s initials or
recognized trade-mark.
=Screw Threads.=--The screw threads must, unless otherwise stated,
be of the standard Whitworth thread, be cut full, and conform to the
government inspector’s standard gages. Contractors may send their gages
at any time to the chief inspector to be checked and compared with the
standard gages.
=General Conditions.=--The contractor is to supply, with the first
delivery, a full-sized tracing, on tracing cloth, of the cartridge he
is delivering. The contractor will also supply, free of charge, samples
of the metal from which the cases are to be made, if requested by the
chief inspector to do so. The samples should not be less than 6 by 2
inches. Cases in stock, that is, cases made before the date of the
contract, must not be submitted for acceptance under a given contract.
The cartridges should be delivered in lots of not less than 400. If
less than 400 are delivered, the number of rounds to be fired in
proof will be the same as if the delivery were the full 400. If, on
examination of twenty per cent of a lot, it is found that departures
from approved design, or defects of any nature, which involve rejection
of the cases, average twenty-five per cent of the number examined, the
whole of the lot will rejected.
=Proof.=--(a) Not less than one-half per cent will be fired in proof.
At least one cartridge from each 400 delivered will be fired three
times, one round being with a proof charge, and the cartridge being (if
necessary) reformed after each round. In each remaining cartridge, one
proof and one service round will be fired.
(b) The cartridge must load and extract easily, and must not split or
develop any flaw or crack on firing.
(c) The cartridge may be sectioned after firing; the section must show
no cracks.
(d) The maximum pressure is not to be more than 19 tons per square inch.
(e) If, in the proof of any delivery, defects appear which involve
the serviceability of the article, additional proof may be taken from
any other delivery not finally closed, to ascertain if the defect
is general or not. Should the cases fail at this further proof, the
delivery will be rejected without reference to the original proof.
The total proof of any delivery shall not exceed five per cent of the
number delivered.
=Replacement of Proof.=--The contractor will be required to replace
all cartridges expended in proof free of charge, and when the order is
approaching completion, he will be informed by the inspector how many
are required to complete the number on the order, exclusive of the
cartridges so expended, which, whether fired or otherwise tested, will
become the property of the government.
=Packing.=--All packages will be so marked that the goods contained
therein may be readily identified with the invoice. Unless specified
herein that the packing cases or other packing material will 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 of the cartridge cases,
they will be disposed of, and in such circumstances the contractor will
not be entitled to make any claim for compensation. The packing cases
must be marked “Returnable” or “Non-returnable.”
[Illustration: Fig. 1. British 18-pounder Quick-firing Cartridge Case,
giving Complete Dimensions, and Bore of Quick-firing Field Gun]
=Spontaneous Cracking.=--Any cartridge found to be cracked before or
after filling, but before firing, is to be replaced by the contractor
if such crack is discovered within six months of the date of acceptance
of the cartridge in question, which date is stamped on it.
The cartridges may be inspected during manufacture by, and after
delivery will be subjected to testing by, and to the final approval
of, the chief inspector, Royal Arsenal, Woolwich, England, or an
officer deputed by him.
=Primer.=--The primer is to consist of the following parts (see Fig.
2): body _A_; closing disk _B_; anvil _C_; plug _D_; cap _E_; tin foil
_F_; ball _G_; paper disk _H_; gun powder _I_; and Pettman cement. The
body is to be made of composition metal known as Class “A” or “B.” All
other metal parts of the primer, except where otherwise specified, are
to be made of brass. The brass is not to contain more than 0.3 per
cent of lead, nor to have more than one per cent of total metallic
impurities. The Class “A” or “B” metal is to be in accordance with
the following requirements: It must be perfectly straight, uniform
in diameter, and free from cracks or flaws, and must be capable of
standing the following minimum tests:
+---------------------------------+----------------------------------+
| Tenacity, Tons per |Elongation in Per Cent in such a |
| Square Inch | Test Piece as can be furnished, |
| | provided that |
+---------------+-----------------+ |
| Yield | Breaking | Length / √Area = 4 |
| Point | Stress | |
+---------------+-----------------+----------------------------------+
| Class “A”, 20 | Class “A”, 30 | Class “A”, 20 per cent |
| Class “B”, 12 | Class “B”, 20 | Class “B”, 30 per cent |
+---------------+-----------------+----------------------------------+
Pieces of the metals it is proposed to use in the manufacture must be
submitted free of charge by the contractor, for testing, when requested
by the chief inspector.
=Body.=--The exterior of the body is to be turned and threaded and a
flange formed. Two slots are to be cut in the head for the key. The
interior is to be bored, cupped, and threaded. The exterior of the body
is to be lacquered with a lacquer consisting of:
Seedlac 1 pound.
Turmeric 8 ounces.
Spirit, Methylated 8 pounds.
=Screw, Plugs and Copper Ball.=--A plug having one end turned to form
an anvil, which is to be free from burrs, is to be threaded to suit
the body. The interior is to be turned out to receive the soft copper
ball, and three fire holes bored. A plug is also to be threaded to suit
the body, having an annular recess turned on the inner side, and three
fire holes bored.
[Illustration: Fig. 2. Primer for British Quick-firing Shrapnel and
High-explosive Shell Cartridge Cases]
=Cap.=--The cap is to be made of copper and the interior is to be
varnished with varnish composed of:
Finest orange shellac 2 pounds 2 ounces.
Spirit, Methylated 8 pounds.
The specific gravity of the varnish is to be 0.885. It is then to be
charged with 1.2 grain of the following composition (figures give parts
by weight):
Sulphide of antimony 18
Chlorate of potash 12
Ground glass 1
Meal powder 1
Sulphur 1
The composition is to be pressed into the cap with a pressure of 800
pounds. A tin-foil disk, lacquered on one side, is then to be placed
on the composition with the lacquered side outwards, and placed under
a pressure of 400 pounds. It is then to be varnished with a varnish
composed of:
Finest orange shellac 2 pounds 2 ounces.
Seedlac 1 pound.
Turmeric 8 ounces.
Spirit, Methylated 16 pounds.
The specific gravity of this varnish is to be 0.865.
The lacquer for the tin-foil disk before insertion is composed of:
Seedlac 2 pounds.
Turmeric 1 pound.
Spirit, Methylated 16 pounds.
The specific gravity of this lacquer is 0.85.
The cap is to be externally coated with Pettman cement before inserting
in the body, and then a fillet of Pettman cement is formed between the
body and cap; Pettman cement is made from the following ingredients:
Gum shellac 7 pounds 8 ounces.
Spirit, Methylated 8 pounds.
Tar, Stockholm 5 pounds.
Red, Venetian 20 pounds 12 ounces
=Gun Powder.=--The primer is to be filled with R. F. G.^2 powder, the
screw plug being first screwed in and fixed by three small punch blows,
and the fire holes covered by a disk of paper secured with Pettman
cement.
=Closing Disk.=--A brass disk having a paper disk secured to it on the
inner side by Pettman cement is to be placed on the top of the powder,
and a ring of Pettman cement painted round the edge of the disk where
the metal will be burred over onto it. After the primer is burred over,
the whole of the exterior of the disk will also be coated with a thin
layer of the cement.
=Marking and Delivery.=--The primers will be marked with the numeral,
serial number, contractor’s initials or recognized trade-mark, and
date of manufacture. The primers will be delivered in lots of 1000,
an additional 20 being supplied for proof with each 1000, or any less
number supplied. In the event of further proof being required, the
primers will be taken from the lot.
=Proof.=--A percentage of the primers will be selected indiscriminately
for proof.
(a) The primer when screwed into a steel block must fire correctly with
a 1-pound weight falling 25 inches, and ignite a puff consisting of 4
drams of R. F. G.^2 powder enclosed in one thickness of shalloon, in a
12-inch vent with special receiver, or when proved in any gun for which
approved, it must ignite the charge without hang-fire.
(b) A miss-fire, hang-fire, pierced cap, or serious escape of gas
through or around the primer will cause rejection.
(c) The falling weight is to have a point of the same shape as the
service striker.
(d) Should the firing proof or examination of any delivery bring to
notice any defect or defects which, in the opinion of the chief
inspector, affect the serviceability of the primers, the delivery in
question may be rejected, or further proof taken at his discretion,
not only from the particular delivery, but from any others made by the
contractor which may be under inspection, to ascertain whether the
defect is general. Should any primers fail at these further proofs,
the delivery or deliveries will be rejected without reference to any
previous proof.
If, on examination of twenty per cent of a lot, it is found that
departures from approved design or defects of any nature which involve
rejection of the defective primers average 25 per cent of the number
examined, the whole of the lot will be rejected. The contractor will be
required to replace free of charge all primers expended in proof and
examination, which, whether fired or otherwise tested, will become the
property of the government.
[Illustration: Fig. 3. British Cartridge Clip]
=Specifications for Cartridge Clip.=--The general dimensions for the
cartridge clip are given in Fig. 3. The clip is made from hard-rolled
sheet brass in one piece. Four projecting arms are to be formed; the
ends of each are bent over as indicated. The clip is sand-blasted, and
lacquered with a lacquer composed of:
Vegetable black 1 pound.
Seedlac 1¹⁄₂ pound.
Turpentine (1 quart) 2 pounds.
Methylated spirits (6 quarts) 12 pounds.
One arm is coated with paint consisting of:
Vermillion, dry 2 ounces.
Shellac, dry 1 ounce.
White hard varnish ³⁄₄ ounce.
Spirits, Methylated 1¹⁄₂ ounce.
=Loop.=--The loop is to consist of 13 inches of “webbing, cotton, ¹⁄₂
inch,” threaded through the clip and sewed. Three yards of webbing,
selected from the bulk, are to be submitted to the chief inspector
before being used. The webbing submitted will be cut into lengths of 11
inches and the ends of each length securely fixed in the clamps of a
testing machine, the clamps being 7 inches apart. The strain will be
gradually increased until the sample breaks. The breaking strain must
not be less than 200 pounds.
=Delivery.=--The clips will be delivered in lots of 1000. If, on
examination of 20 per cent of a lot, it is found that departures from
approved design, or defects of any nature, which involve rejection of
the clips average 25 per cent of the number examined, the whole of the
lot will be rejected.