THE .303 BRITISH CARTRIDGE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A Mk II black powder round produced by Royal Laboratories for use in the Lee-Metfords, very rare. It has the small primer pocket.

Development

The .303 British round is more than just a military cartridge; it is a symbol of a once great empire which for better than seventy years it helped build. This venerable cartridge dates officially from 1888 when it was adopted by a British Royal Ordnance committee along with the Lee-Metford rifle, both the cartridge and the rifle were of foreign origin. The .303 was the result of Major Eduard Rubin, then Superintendent of the Swiss Government Arms Laboratory at Thun (of Schmidt-Rubin fame) and his experiments and development of a straight/tapered walled cartridge in 7.7mm incorporating a crimped on driving band. The driving band system proved inferior for the pressures generated in the cartridge and thus a bottleneck case was developed. The Lee-Metford was the invention of James Paris Lee, a Scot who later became a naturalized American; however, the word "Metford" pertains only to the rifling pattern of the barrel. This rifling form was developed by William Ellis Metford an English civil engineer.

The first .303 British had the familiar bottle necked shape of today's .303 but used 71.5 grains of black powder compressed to fit the small case. Its official name was Cartridge, S.A., Ball, Magazine Rifle, Mark 1, Solid Case, .303inch and was topped with a 215 grain cupro-nickel jacketed, round nose bullet of .311 inch diameter and had a velocity of around 1850 fps. In 1892 the new Nitro-glycerin based Cordite smokeless powder was adopted as the standard propellant but still retained the 215 grain bullet. This smokeless round was designated as the Mark I* and gave a velocity of 2060 fps. The shallow elliptical Metford rifling that worked so well at reducing bore fouling when black powder was used, quickly proved incapable of withstanding the erosive effects of the hotter burning Cordite and barrels were quickly shot out. RSAF Enfield tackled this problem by designing a new rifling pattern that had sharper edges, was cut deeper, and had lands and grooves of equal width, this pattern was aptly named Enfield rifling. Adopted in 1895 the new barrel fitted to the same Lee action became the Lee-Enfield Magazine Rifle Mark I, or Magazine Lee-Enfield (MLE).

Having effectively solved the erosion problem, the British had to move onto the next issue at hand, the 215 grain bullet wasn’t stopping the enemy. Plainly put by today’s understanding of terminal ballistics the heavy 215 grain, 30 caliber bullet was just not going fast enough to impart its energy into a human body. However, at the time this was not completely understood and several experiments by the British to improve the performance of the round commenced. One of these attempts was undertaken by the British arsenal at Dumdum, India where the bullet was manufacture with an exposed lead tip allowing for rapid expansion. The bullet worked quite well, but drew very negative responses from the other civilized nations and culminated in them being specifically forbidden in the Hague Convention of 1899. Not to be completely deterred, and spurred on by the German invention of the spitzer bullet in 1905,  England devised a 174 grain pointed bullet of their own. To help the terminal effects of the bullet, working within the ballistic parameters of the .303 cartridge and pressure limits available in the Lee action, and to abide by the Hague Convention, they lightened the nose of the bullet by first filling the nose with aluminum followed by the lead core. The result was a longer more aerodynamic bullet good for accuracy but upon impact became very unstable and tumbled. In 1910, the Cartridge S.A. Ball .303 inch Cordite MarkVII was adopted, using the 174 grain bullet and was loaded to produce a muzzle velocity of 2440 fps, this round would remain the standard loading until replaced by the 7.62 x 51mm NATO cartridge. The only other significant 303 cartridge developed was the MkVIII round, which was intended for use in the Vickers Machine Gun. This round had a nitro-cellulose powder charge with a 175 grain boat tailed, steel jacketed bullet having a muzzle velocity of 2550 fps.

During the course of World War I, as with the production of the P-14 rifle, Britain turned to the United States to help with ammunition production. This call was answered by Dupont and their IMR 16 single based nitrocellulose powder. IMR 16 closely duplicated the performance of the Cordite loading, but had the advantage of burning cooler and as the ballistic characteristics was near identical to the Cordite loaded round, it kept the Mark VII classification, but with the addition of a "Z" (Mk VIIZ) to denote the propellant change. The nitrocellulose powder also offered the added benefits of not having to alter existing or future rifles’ sights and because of its cooler burning, prolonged the normal service life of the Enfield barrel. After the war, this powder was offered for public consumption as IMR 3031.

Cautionary Notes

Caution should be exercised when considering the use of the MkVIII round though, especially in older Long Lee’s or SMLE’s. According to Labbett & Mead's ".303 Inch" ballistics for the MkVIII it is listed as 20-21 tons/sq versus 19.5 for the MkVII with a muzzle velocity of over 2500fps as opposed to the 2440fps of the MkVII. At 2240lb/ton, this means pressures of up to 47,000psi, which is chasing at the heels of, if not breaching, current published safe pressures for the Lee action. I must thank Dr. Justin Moretti for bringing this potential hazard to my attention.

The .303 British must not be confused with the .303 Savage, the Savage is a totally different cartridge and is in no way related to the .303 British.

The 303 and Hunting

Identifying the .303 British Cartridge

The British, outside of designating a Mark to the various .303 cartridges, also developed a letter code series to further identify specific type or special purpose ammunition.

"B"

British .303 incendiary cartridges may be identified by a blue primer annulus and for aircraft class ammunition the bullet tip is also colored blue. However, if all the paint is worn off they can also be identified by the headstamp. The letter "B" is the code for incendiary and the Roman numeral, which follows, is the Mark of the series. The letter "Z" which may follow the Roman numeral indicates that the propellant used is nitrocellulose powder instead of Cordite.

"G"

The British had a =n extensive tracer series including three means of identification, consisting of headstamp code with the letter "G" as the key, red primer annulus, and colored bullet tip for aircraft grade ammunition. The letter "Z" is included in the headstamp when the propellant used is nitrocellulose rather than Cordite. Bullet jackets may be cupro-nickel or gilding metal. The series is:

VIIG        - Previous to 1928,
GI            - Burning for 500 yds, all services,
GII           - Burning for 1000 yds, Land service,
GIII         - Burning for 800 yds, Naval service,
GIV         - Burning for 550 yds, Air service, White Tip,
GV           - Burning for 550 yds, Night Tracer, Air service, Gray Tip,
GVI         - Burning for 550 yds, Air service, White Tip, replaced GIV

"W"

Armor piercing ammunition was identified with the letter "W" as the key.

The Ball Cartridge

The most common surplus .303 ammunition found today will be:

Cartridge, Small Arms, Ball, .303 Inch, Mk VII - 174 grain, Flat Base, Cupro-Nickel Jacketed round. Cordite propellant, muzzle velocity 2440 fps.

Cartridge, Small Arms, Ball, .303 Inch, Mk VIIZ - 174 grain, Flat Base, Cupro-Nickel Jacketed round. Nitrocellulose propellant, muzzle velocity 2440 fps.

Cartridge, Small Arms, Ball, .303 Inch, Mk VIIIZ - 174 grain, Boat Tail, Cupro-Nickel Jacketed round. Nitrocellulose propellant, muzzle velocity 2440 fps.

Reading the Headstamp

Commonwealth headstamp information is placed on the head of the cartridge in a triangle fashion. This information should be read from the top, left and then right. See figure 1.

Blank Cartridges

There were a vast number of blank firing cartridges assembled for use in the Lee-Enfield. These cartridges are easily distinguished by their bold pedal crimp at the neck of the round. See Figure 2.

Drill Rounds

 

 

 

 

Figure 1

Commonwealth headstamp information will always include the date of manufacture (either 2 or 4 digits), the manufacturer and the type of loading. In this case, the headstamp indicates (reading from top, left and right) that the cartridge was manufactured by Royal Laboratories in 1926. It is a Mk VII (Cordite propellant) Armor Piercing round.

 

 

 

 

 

 

Figure 2

Typical Blank Cartridges

 

 

 

 

 

 

 

 

 

 

Figure 3

Drill Rounds

 

 

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