The Best Rifle Cartridge of World War I?

Was the British .303 Mark VII the best Rifle Cartridge of the Great War?

November 22, 2021 By David M. Fortier, Senior Field Editor

A wide variety of modern and obsolete cartridges for the time saw service during World War I. These included smokeless and black powder designs with rimmed, semi-rimmed and rimless cases throwing bullets from 6.5mm to about 11mm. A number of cutting edge rifle designs with modern cartridges faced off against each. Plus, there were many obsolete rifles chambered for older cartridges, and many captured rifles were issued to second line units. But, was there one cartridge which stood out, which was the best? One cartridge which gave particularly good service during the war was the British .303-inch Mark VII ball load. So let’s examine that.

Unlike its contemporaries the .303 British was originally a black powder cartridge when it was first adopted on 2nd February 1889. The original .303 Mk I Ball load consisted of a 215-grain round nose jacketed bullet on top of 75.5 grains of black powder. The propellant though was soon changed to Cordite, and this remained basically the same up through the Mk VI ball loading. The design of the projectiles fielded varied, with the Mk II being similar to the Mk I but with a thicker and improved jacket. Then things got interesting, with the Mk III – V loads all being designed to improve terminal performance. The Mk III featured a 215-grain Soft Point projectile while the Mk IV and V were topped with Jacketed Hollow Points. The Soft Point and Jacketed Hollow Point loads were used in the colonies to good effect on Boers and natives. The effect was good enough the Dutch brought it up at the Hague Convention of 1899. This in turn led to a new Full Metal Jacket Mk VI load replacing the earlier loads in 1904. This was a round nose design similar to the Mk II.

The big change came with the adoption of the famous Mark VII ball round in 1910. This consisted of a 174-grain flat-base Spitzer on top of 37-grains of Cordite MDT 5-2. Velocity was 2,440 fps giving it a maximum indirect fire range of 3,700 yards when fired from a Vickers Machine Gun. It was this load, the Mark VII, which would be standard issue to British forces during World War I. It would see use in the Lee Enfield No. 1 Mk III and Pattern 14 rifles, Lewis and Vickers Machine Guns and be fielded on the ground, the ocean and in the air. It would serve throughout the far-flung empire during the war, and prove itself so well, that it would remain in service in the post-war years, serve through World War II and into the Cold War.

Best Rifle Cartridge of World War I — The .303 “British” cartridge evolved through seven “marks” prior to World War I. Note the round nose Mk VI on the left and the Mk VII on the right.

The .303-inch cartridge is a rimmed bottleneck design. It’s interesting to note the military cases featured beveled rims to prevent “rim lock” when feeding from box magazines. Case length is 2.222-inches or 56.4mm with a 0.540-inch rim diameter and 0.460-inch base diameter. Overall length is 3.075-inches. Typically it was loaded with a Berdan primer. Looking at it from the outside doesn’t really reveal this cartridge’s secrets though.

Taking a look inside you will note the flat base projectile, card over-powder wad and long strands of Cordite. It’s interesting to note the Cordite was inserted into the case before the necking operation. While the flat-base projectile seems a bit out of place in 1910, there is a typically British reason for it. The British military did not deny the long range superiority of the boat tail (they referred to it as streamlined) projectile over the flat-base. They readily admitted a boat tail projectile has a greater capacity for overcoming air resistance, flatter trajectory, higher retained energy at longer ranges, and a longer range.

However, they also felt that it was far easier to manufacture a square (or flat) base projectile and therefore it was easier to maintain the standards of manufacture. This in turn would produce a more consistent and accurate projectile. Poorly manufactured projectiles may give rise to oscillation in flight producing poor accuracy at anything but short range. They felt that since mass production is at its peak during wartime, it was likely boat tailed bullets manufactured under such conditions might lack the careful finish needed to guarantee accuracy. So, they retained the ballistically inefficient, but easier to manufacture flat-base design. At the typical distances infantry engaged at with rifles during World War I, inside 400 meters, the flat-base projectile was not a real drawback.

Things get interesting though when you look inside the 174-grain FMJ spitzer projectile. The Cupro-Nickel jacketed projectile is an interesting design specifically developed to increase terminal performance. Keep in mind, the .303 British is one of the only military rifle cartridges to have had SP and JHP ammunition developed as standard issue and used in combat. The British authorities, with recent combat experience in the colonies, felt terminal performance was very important. So, while adhering to the letter of the Hague Convention the Mk VII didn’t adhere to the spirit of it. How did they improve its terminal performance? While the rear 2/3rds of the bullet core is lead, the front 1/3^rd is lightweight aluminum (or plastic, wood pulp or compressed paper). Why? This moves the center of gravity of the projectile to the rear, resulting is an early yaw cycle on impact. So, instead of punching cleanly through a target, the projectile yaws and tumbles due to the heavier base, creating a larger permanent wound cavity and improving terminal performance.

A classic design, the .303 Mk VII soldiered on in British service until finally replaced by the 7.62x51mm NATO cartridge in the 1950s. So, it lived a very long and successful life. Was the .303-inch Mk VII the best rifle cartridge/load fielded during World War I? Being a rimmed design is certainly a drawback. While not an issue in the Lee Enfield series of rifles, or the Vickers machine gun, the rimmed case design would prove a drawback in automatic weapons. As a “universal” type of cartridge fielded in rifles, light machine guns and the Vickers Gun the 174-grain bullet weight proved a good compromise. But it was not the “ideal” solution for the individual weapons platforms. The rifles would have been better served with a 130-150-grain FMJ projectile which would have been lighter, needed less material to manufacture and had a flatter trajectory at normal infantry engagement distances. In 1938 the Vickers would receive a slighter faster, 2,525 fps, 175-grain FMJ-BT load, the Mark VIIIZ for long range indirect fire use. This extended the Vickers’ range out to 4,500 yards.

The 7x57mm Mauser had out-performed the earlier .303-inch loads in combat in South Africa prior to World War I. The .303 was actually slated for replacement. However, the Guns of August had kept it in service, and the Mk VII load performed well in Western Europe. But, anyone who has shot the .303 at distance will note it is a bit lazy in the wind and not as flat as some of its contemporaries. So, the .303-inch Mk VII ball load was a good performing load, but not the best of World War I.

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About the Author:

David M. Fortier has been covering firearms, ammunition and optics since 1998. He is a recipient of the Carl Zeiss Outdoor Writer of the Year award and his writing has been recognized by the Civil Rights organization JPFO. In 2007 he covered the war in Iraq as an embedded journalist.