Great Britain also felt the need to replace both Sten submachine guns and SMLE No.4 bolt-action rifles with more modern equipment. The research and experience clearly showed that it is entirely possible to replace both of these weapons with single new weapon, with effective range of fire of no more than 1000 yards and with selective-fire capability. This weapon, of cause, required a new cartridge, which was developed after extensive research and development. This cartridge, an "ideal" from British point of view, was of .280 caliber (7mm) and had a bottlenecked case 43 mm long. The pointed bullet weighted 9.08 g (140 grains) and had muzzle velocity of about 745 m/s (2445 fps). The rough comparison of this round against other most common modern cartridges can be found in the table below. Basically, this cartridge offered significant advantage in effective range and penetration against not only 9x19mm Luger pistol cartridge, but also against 7.92x33mm Kurz German and 7.62x39mm Soviet intermediate cartridges, producing slightly more recoil, which was still significantly less than of .303 British rifle cartridge or latter 7.62x51mm NATO cartridge.
Enfield EM-2 / Rifle, Automatic, caliber .280, Number 9 Mark 1 (Great Britain)
EM-2 assault rifle, officially adopted in Britain as Rifle, Automatic, No.9 Mk.1 but never put into service
Note that the backup sights are in raised position.
from let to right: British experimental .280 (7x43mm) cartridge for EM-2; Soviet 7.62x39mm M43; US/NATO 5.56x45mm (.223 Rem); US/NATO 7.62x51mm (.308 Win)
Caliber: 7x43 mm (.280 British)
Action: Gas operated
Overall length: 889 mm
Barrel length: 623 mm
Weight: 3.41 kg with empty magazine
Rate of fire: 450 - 600 rounds per minute (depends on source)
Magazine capacity: 20 rounds
comparison table: British .280 caliber intermediate cartridge vs. most common modern military cartridges
ballistic data is estimated using Norma ballistic calculator and Sierra Bullets data on ballistic coefficients.
| |
5.56x45mm NATO |
7x43mm EM-2 |
7.6x39mm M43 |
7.62x51mm NATO |
| bullet weight |
4.01 g (62 gr) |
9.08 g (140 gr) |
7.9 g (122 gr) |
9.72 g (150 gr) |
| bullet velocity, at muzzle |
921 m/s |
745 m/s |
710 m/s |
860 m/s |
| bullet velocity, at 300 yards (273 meters) |
585 m/s |
570 m/s |
470 m/s |
674 m/s |
| bullet velocity, at 550 yards (500 meters) |
385 m/s |
450 m/s |
341 m/s |
516 m/s |
| bullet energy, at muzzle |
1700 J |
2519 J |
1991 J |
3594 J |
| bullet energy, at 300 yards (273 meters) |
686 J |
1475 J |
872 J |
2207 J |
| bullet energy, at 550 yards (500 meters) |
297 J |
919 J |
460 J |
1294 J |
http://world.guns.ru/assault/as59-e.htm
The 5.56 mm round was based on the doctrine of overwhelming volume of fire. In combat Small weapons are used to kill, to suppress, to deny movement or to force movement. In a conventional war a high volume of fire is a good fit and a small round permits soldiers to carry the hundreds of rounds necessary to accomplish this. The limited warfare we are now presented with places a higher value on stopping power and penetration.