.276 Enfield

Type

Rifle

Place of origin

United Kingdom

Production history

Designer

Royal Laboratory

Designed

1912

Produced

1912–1916

Specifications

Case type

rimless, bottleneck

Bullet diameter

.284 in (7.2 mm)

Neck diameter

.323 in (8.2 mm)

Shoulder diameter

.460 in (11.7 mm)

Base diameter

.528 in (13.4 mm)

Rim diameter

.521 in (13.2 mm)

Case length

2.35 in (60 mm)

Overall length

3.23 in (82 mm)

Case capacity

72 gr H₂O (4.7 cm³)

Primer type

Berdan

Ballistic performance

Bullet mass/type	Velocity	Energy
165 gr (11 g)	2,800 ft/s (850 m/s)	2,888 ft·lbf (3,916 J)

Source(s): [1]

The .276 Enfield was an experimental military rifle cartridge developed in conjunction with the Pattern 1913 Enfield (P'13) rifle. Development was discontinued by the onset of World War I.

The .276 Enfield was designed with the intent of being more powerful than the .303 British cartridge used in the Lee–Enfield rifles and to be at least similar in size and performance to other large, powerful early 20th century military rifle cartridges, like the 7.92×57mm Mauser, .30-06 Springfield and 7.5×55mm Swiss GP11. Before arriving on the RL18000C 1913 trails round dozens of .256 and .276 cartridge case and projectile iterations were developed and tested over several years. The longest .276 cartridge iterations featured an overall length of 3.587 in (91.11 mm) and a case length of 2.76 in (70.10 mm).

To allow for the dimensions and higher muzzle energy .276 cartridge a new experimental rifle was developed. The experimental Pattern 1913 Enfield rifle featured a Mauser-type action that was very substantial and designed to be stronger than the Lee–Enfield action. While the .303 British round has a larger-diameter projectile than the .276 Enfield, the .276 Enfield cartridge case is larger and contains more propellant developing higher chamber pressures and higher muzzle velocities; as such, it is more powerful than the .303 British. The .303 Mk VII round introduced in 1910, for instance, has a projectile weight of 174 gr (11.28 g) and a muzzle velocity of 2,441 ft/s (744 m/s), while the .276 has a projectile weight of 165 gr (10.69 g) and a muzzle velocity of 2,785 ft/s (849 m/s).

The combination of a slimmer more aerodynamic projectile with a higher sectional density propelled at a higher muzzle velocity and designed to travel at faster velocities gave the .276 Enfield better ballistics than the .303 British. The .276 Enfield was also rimless to ensure greater reliability in magazine-fed weapons, a problem with the older .303 British round. However, due to the approach of World War I, the .276 Enfield was not implemented for military service.

Several developmental versions of ammunition were prepared beginning in 1910 before approximately 1,000 Pattern 1913 Enfield rifles with 600,000 rounds of RL18000C trials cartridges were distributed to troops in 1913. The great majority of troop trial ammunition was manufactured by the Royal Laboratory with the headstamp simply "R^L", but it was also made by Kings Norton, Kynoch and Greenwood and Batley. Although the troop trial round was never formally approved, it was referred to as "Cartridge S.A. Ball .276 inch Mark I" in some documents and on the packet labels. The troops' trials rifles and ammunition were distributed to the musketry school at Hythe, to one squadron in each of three cavalry regiments, and to one company in each of eight infantry battalions. One of the cavalry squadrons was stationed in South Africa and one of the infantry companies was stationed in Egypt. The remainder of the units were in the United Kingdom. Cartridges were packaged in 5-round stripper clips similar to those used by the Mauser Gewehr 98 and M1903 Springfield rifles. Ball ammunition was loaded with 49.3 gr (3.19 g) of cordite MDT behind 165 gr (10.69 g) cupronickel-jacketed .282 in (7.16 mm) diameter 1.365 in (34.67 mm) long spitzer bullets. The bullet core was made of 98% lead and 2% antimony alloy. Drill rounds containing no primer or powder have been reported in two versions. One has a tin-plated case with the standard bullet, and the other has a round-nose wood bullet with an unplated brass case. Inert Dummy or Inspection, RL20408 blank and proof ammunition was also produced based on the case of RL 18000C. Proof test ammunition was made in a RL 18000.B(i) variant for use with pressure barrels and a RL 18000.B(j) variant for proofing rifles.

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