.303-inch

303

.303-inch ammunition was the standard round adopted by the British in 1889, for both Land and Naval, and subsequently Air, service. Through it’s various iterations, the Mk. VII Ball ammunition was that in service at the time of the introduction of the Mk. I Vickers. The development of the ammunition was then closely linked to the development of the different weapons and the various roles of the Vickers led to various demands for different types of ammunition, including explosive, tracer, armour piercing and many others. These are all covered below.

Calibre specification
Metric (mm) Imperial (in)
Calibre 7.7 .303
Name: British
Case Type: Rimmed, bottlenecked
Bullet Diameter: 7.90
Case Length: 56.1
Rim Diameter: 13.44
Neck Diameter: 8.54
Shoulder Diameter:
Base Diameter: 11.65
Total Length: 76.7
Weight: 28.6 grammes
Primer: Berdan
Year Introduced: 1888
Also known as:
  • .303 Lee Metford
  • .303 Lee Enfield
  • .303 Vickers
  • .303 Bren
  • 7.7x56R
  • 7.7mm Breda
  • 7.7mm Type 89
  • 7.7mm Patrone S 272(e)
  • DWM 371, 453

Variants

Ball

Summary of Approved Marks of .303 inch Ball Ammunition
Mark No. Approved Propellant Primer Bullet (grains) Envelope material Cannelure Headstamp includes Remarks
7 1910 Cordite Berdan 160 Cupro Nickel None “VII” Pointed bullet (as opposed to round nosed bullet of Mk. VI)
7 1910 Cordite Berdan 174 Cupro Nickel, Cupro Nickel Clad Steel, Gilding Metal, Gilding Metal Clad Steel One “VII” or “7” Pointed bullet
7z 1916 Nitrocellulose Berdan 174 Cupro Nickel, Cupro Nickel Clad Steel, Gilding Metal, Gilding Metal Clad Steel One “VIIz” or “7z” Pointed bullet
8z 1916 Nitrocellulose Berdan 175 Cupro Nickel, Gilding Metal One “VIIIz” or “8z” Pointed bullet with boattail

Cartridge, SA, Ball, .303-inch, Mk. VII (Mk. 7)

First approved in March, 1910, so was the variant in service at the time the Vickers was adopted. The previous variant, the Mk. VI, was in service with the Maxim but the Vickers was not chambered for it. A number of early manuals make reference to the Mk. VI and comparison with the Mk. VII.

It was approved for Land and Naval service in November, 1910, and extended to Air Service in May, 1919 (although likely to have been used extensively before this date).

It used a cordite propellant. It was originally loaded with one glazedboard disc but this was substituted, in 1933, for strawboard to minimise the danger of fired wads to aircraft armed with .303-inch machine guns.

The muzzle-velocity was 2440 feet per second, with 19½ tons per square inch chamber pressure.

One of the major-issues for aircraft use of the Vickers, by the Royal Flying Corps and Royal Air Force, was the quality of ammunition. A special ‘purple label’ ammunition was issued for practice. They also produced a ‘reduced charge’ variant (Cartridge, SA, Ball, .303-inch, NC, Mark VII.z.RC) to simulate a No. 1 stoppage in training. It was introduced in September, 1918, and marked with a blue band 1-inch wide.

This was marked with a black-coloured annulus before 3rd September, 1918, when it was changed to purple.

There were a number of issues with different manufacturers’ ammunition being used in machine guns.

INSPECTION TESTS OF S.A.A. AMMUNITION IN MACHINE GUNS

MUNITIONS DESIGN COMMITTEE SMALL ARMS SECTION Minute (S)42. 25 March 1916.

At a conference held on 10.2.16 it was decided that:-

1. The .303 Maxim gun should be used in the test.

2. The gun should be adjusted so that the lock should go home clear on the .068 cartridge head gauge, and that there should be a check on the 0.69 gauge, the latter being measured by the insertion of a washer or washers in the connecting rod.

3. C.I.S.A. would consider an amendment to paragraph 77 of the .303 Vickers’ Machine Gun Handbook, 1914.

4. C.I.S.A. would give due importance to the decision under (2) in dealing with the repair of machine guns.

D.G.M.D. asks C.I.W. to take the necessary steps to give effect to 1 and 2.

C.S.O.F. reports to D.G.M.D., 8.3.16, that trials have been carried out with O.F. proof of cases. It has always been the custom to prove our own output at a pressure 1 ton higher than service ammunition, to allow for possibly worse conditions in the gun than in our proof gun.

1,000 rounds were fired in the Maxim, with the following clearances and results:-

No. of rounds. Head clearance. Casualties.
1,000 .064″ Nil.
1,000 .0665″ Nil.
1,000 .069″ 2 partial separations.
1,000 .0715″ 1 separation.
6 showing signs.
1,000 .074″ 4 partial separations.
8 showing signs.

A repeat trial was then carried out:-

No. of rounds. Head clearance. Casualties.
1,000 .065″ Nil.
1,000 .068″ 2 showing signs of separation.
1,000 .069″ 1 separation.
6 showing signs.

From these results, which were all carried out with lots of cases which had gone successfully through original proof, it is not clear what clearance should be employed with the ton extra pressure, and it is not thought safe to drop the latter. Tentatively, a clearance such that .067 will just touch will be tried, but until the point is settled we may have difficulty in meeting the new regulations.

C.I.W. reports to D.G.M.D., 13.3.16, that the following four deliveries have, after rejection under the old test, been accepted after re-test under new conditions:-

Kynoch 14.12.15. No. of rounds. Casualties.
1st proof 2,000 9 separations.
4 partial separations.
15 stretched metal.
Re-test 2,500 13 partial separations.
10 stretched metal.
Greenwold and Batley, 16.1.16
1st proof 500 3 burst bases.
1 separation.
Re-test 1,500 4 very slight bursts.
1 partial separation.
Eley, 3.12.15.
1st and 2nd proofs 850 3 separations.
5 partial separations.
1 burst body.
Re-test 1,000 9 partial separations.
Eley, 4.12.15
1st, 2nd and 3rd proofs 1,500 45 separations.
35 partial separations.
34 stretched metal.
1 burst base.
Re-test 1,000 1 separation.
12 partial separations.
33 stretched metal.

D.D.G.(S) informs D.D.G.(E) that he was told by C.I.W. that the trouble with Kynoch’s was due to faulty brass, but that it was now over. That the trouble with Greenwood and Batley was one of manufacture, and this was now also over. That the trouble with Eley’s still existed, being due very largely to faulty brass. He is of the opinion that it is imperative that immediate steps should be taken to see that none but the best material is obtained by, or supplied to, manufacturers of small arms ammunition.

E.M.2 informs D.D.G.(S), 21.3.16, that he is taking this matter up with Eley Bros., and now that supply of brass and cupro-nickel strip for .303 cartridges has been transferred from the Metal Department to his department the points raised in the preceding Minutes will have his special attention. He has written to all S.A.A. manufacturers drawing their attention to the fact thay they are responsible for the testing of all materials used by them.

Referred to the Munitions Design Committee to note.

ACTION TAKEN- Reported to D.D.G.M.D.(S). Noted by the Committee.

Cartridge, SA, Ball, .303-inch, Mk. VIIz (Mk. 7z)

The ‘z’ indicates the use of nitro-cellulose propellant instead of cordite. It was approved for use in May, 1916, for Land Service.

Cartridge, SA, Ball, .303-inch, Mk. VIIIz (Mk. 8z)

The first boat-tailled ammunition was produced to improve accuracy and stability in flight. It was produced for the Vickers and trialled with 20 specially-produced barrels. The Mk. VIIIz was approved for land service in January, 1938, and became the standard ammunition for use in the Vickers in overhead and indirect fire. It was for sole use in the Vickers but could be used in other weapons in exceptional circumstances where reduced muzzle flash was needed. It was the last variant of the .303-inch ball cartridge.

.303″/.22″ Experimental Machine Gun Short Range Practice Ammunition

A necked-down version of the .303-inch Mk. VII case was used to produce a training sub-calibre round that could be used on 30-yard indoor ranges for training purposes. This came with as a set of cartridges and barrel that could be used in a service gun.

Ammunition details of Cartridges, S.A. Ball, .303-in., Mk. 8z
Muzzle velocity Calculated at 90 ft. – 2440 +- 40 f.p.s
Chamber pressure 19 tons per sq. in. (approx.)
Cartridge Rimmed.
Colour of annulus – purple.
Bullet Nose – pointed.
Base – flat.
Form – “boat tail” – streamlined.
Envelope – gilding metal.
Core – lead and antimony 90/10.
Weight – 175 gr. (approx.)
Propellent N.C.
Charge – 36.5 gr.
Extreme range 4500 yd.
Figure of merit 8 in. at 600 yd.

Tracer

Tracer ammunition was marked with a red-coloured annulus.

Summary of Approved Marks of .303-inch Tracer and Practice Tracer Ammunition
Mark No. Approved Propellant Primer Bullet (grains) Type Trace (yards) Headstamp includes Remarks
Mark I 1915 Cordite Berdan 167 Bright 75 Ball headstamp
VII T Z 1916 Nitrocellulose Berdan 167 Bright 800 “VII T” or “VII TZ”
VII G
VII BZ
1916 Cordite
Nitrocellulose
Berdan 158
168
Bright 800 “VII G” or “GI”
“VII GZ” or “GIZ”
Later became the G Mark I or G Mark Iz
G Mark II
G Mark IIZ
1937 Cordite
Nitrocellulose
Berdan 154 Bright 1000 “GII” or “G2”
“G2Z”
G Mark III 1939 Cordite Berdan 154 Bright 800 “GIII”
G Mark IV
G Mark IVZ
1940 Cordite
Nitrocellulose
Berdan 158 Bright / Air / Day 550 “GIV”
“GIVZ”
White bullet tip
G Mark V
G Mark VZ
1942 Cordite
Nitrocellulose
Berdan 161 Air / Night dark ignition 550 “GV”
“GVZ”
Grey bullet tip
G Mark VI
G Mark VIZ
1942 Cordite
Nitrocellulose
Berdan 151 Bright / Air / Day 550 “GVI” or “G6”
“GVIZ”
White bullet tip
G Mark VII 1944 Cordite Berdan 151 Delayed Ignition 100 yards 1000 “G7”
G Mark 8 1945 Cordite Berdan 169 Delayed Ignition 100 yards 1000 “G8” Degraded ogive
PG Mark I
PG Mark IZ
1945 Cordite
Nitrocellulose
Berdan 154 Bright 800 “PGI”
“PGIZ”
Dark blue band on case

Armour Piercing (A.P.)

Armoured Piercing ammunition was marked with a green-coloured annulus.

Summary of Approved Marks of .303-inch Armour Piercing Ammunition
Mark No. Approved Propellant Primer Bullet (grains) Envelope material Core Headstamp includes Remarks
VII S 1915 Cordite Berdan 174 Cupro Nickel 33 grain steel tip VII S
VII P
VII PZ
1916 Cordite
Nitrocellulose
Berdan 174 Cupro Nickel 80 grain steel VII P
VII PZ
VII F
VII FZ
1916 Cordite
Nitrocellulose
Berdan 155 copper 67 grain steel VII F
VII FZ
semi-armour piercing
VII W
VII WZ
1917 Cordite
Nitrocellulose
Berdan Cupro Nickel 93 grain steel VII W or W I
VII WZ or W IZ
Titles changed in 1927 from VII W or VII WZ to W Mk. I or W Mk. I Z

Incendiary and Explosive

Note: Not all incendiary and explosive ammunition was suitable for synchronised Vickers Guns; however, it is included in this information for completeness.

Incendiary ammunition was marked with a blue coloured annulus. Explosive ammunition was marked with a orange-coloured annulus before the Second World War, when it changed to a black-coloured annulus.

Summary of Approved Marks of .303-inch Incendiary, Explosive and Observing Ammunition
Mark No. Approved Propellant Bullet weight (grains) Filling Headstamp included Remarks
VII K (Brock) 1916 Cordite 149 Potassium Chlorate Ball headstamp, usually
Buckingham Mk. I 1915 Cordite 170 Yellow phosphorous Ball headstamp Round nosed bullet
Buckingham Mk. 2
Buckingham Mk. 2Z
1916 Cordite
Nitrocellulose
137 Phosphorous and aluminium powder “VII B” Pointed bullet
Buckingham Mk. 3
Buckingham Mk. 3z
1918 Cordite
Nitrocellulose
147 Phosphorous and aluminium powder “VII B” Flat tipped bullet
B Mark 4
B Mark 4z
early 1920s Cordite
Nitrocellulose
150 Phosphorous “B IV”
“B IV Z”
Stepped bullet
B Mark 4 z* c.1940 Nitrocellulose 154 Phosphorous “BZ” Stepped bullet
B Mark 6
B Mark 6z
1939 Cordite
Nitrocellulose
157 SR 365 (Barium Nitrate) “B VI”
“B VI Z”
Pointed bullet
B Mark 7
B Mark 7z
1941 Cordite
Nitrocellulose
177 SR 365 (Barium Nitrate) “B VII”
“B VII Z”
Pointed bullet
PSA Mark I 1916 Cordite 155 Nitroglycerine Ball headstamp Copper warheard
PSA Mark 2
PSA Mark 2z
1917
1918
Cordite
Nitrocellulose
167 Nitroglycerine “VII AA” Copper warhead
RTS Mark I 1917 Nitroglycerine No special markings Copper warhead
RTS Mark 2z 1917 Nitrocellulose 168 Nitroglycerine No special markings Copper warhead
O Mark I 1934 Cordite 174 Phosphorous “O I”

Blank Ammunition

Blank ammunition was used with the Blank Firing Attachments. The use of bulleted or long-necked blank was necessary in the Vickers to avoid No. 3 stoppages. The use of ‘short’ blank was officially restricted but it appears that the availablity of the Mk. V blank for all other weapons meant that it was often used in the Vickers, possibly with amendments to the feedblock.

Summary of Approved Marks of .303-inch Blank Ammunition
Mark No. Approved Primer Case Type Remarks
Mark 5 Cordite (also nitrocellulose) 1894 Berdan Ball type Crimped
Mark 6 Cordite, mock bullet 1901 Berdan Ball type, crimped with a mock bullet Case blackened with brass mock bullet
L Mark 7, wood bulleted 1939 Berdan Ball type Uncrimped Yellow wood bullet
L Mark 9 Z 1955 Berdan Ball type Crimped
Machine gun Mark I 1914 Berdan Solid drawn Short body (heavily bottlenecked)

Drill and Inspectors

Note: Early cartridges Marks, related to the Mk. 6 Ball ammunition, have been omitted from the list.

Summary of Approved Marks of .303-inch Drill and Inspectors Dummy Cartridges
Mark No. Approved Description
Dummy Drill Mark 4 1910 Brass case pierced with holes. Pointed wood bullet.
Dummy Drill Mark 5 1917 Reject service case, blackened, pierced with holes. Mark 7 ball bullet.
Dummy Drill Mark 6 1917 White metal case with three flutes. Solid bullet or Mark 7 ball bullet.
Drill D Mark 7 1932 Tinned case with three flutes. Metal clad bullet with aluminium core.
Drill D Mark 8 1941 Brass case with three thin flutes or holes. Red wood bullet and distance piece.
Drill D Mark 9 1943 Brass or chromed case with three thin flutes or holes. Metal clad wooden bullet.
Drill D Mark 10 1954 Chromed brass case with three flutes. Mark 7 ball bullet.
Drill D 1942 Canadian 1942 Chromed brass case with three flutes. Mark 7 ball bullet.
Inspectors Dummy Mark 4 1911 Tinned brass case, service bullet. Weighted to approximate to Cordite ball Mark 7.
Inspectors U Mark 5 1918 White metal or chromed case, pointed bullets of various forms.
Machine gun Dummy Mark 2 1910 Solid steel dummy cartridge with pointed nose, weighted to approximate to cordite ball.

Countries using this calibre


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