05-09-2011, 06:22 AM
A few weeks ago someone asked me to do this. So this was my first-draft shot at it:
OUTLINE SPECIFICATION FOR A LIGHTWEIGHT HIGH-PERFORMANCE SMALL-ARMS CARTRIDGE
The problem
1. Combat experience in Afghanistan has revealed that 5.56x45 NATO ammunition has insufficient range for at least half of the small-arms engagements, and suffers from poor barrier penetration and unreliable terminal effectiveness even within its range.
2. Weapons chambered for the older 7.62x51 NATO ammunition are therefore seeing much more use, but while this ammunition is effective it is heavy and generates high recoil.
3. The aim is to design a cartridge or cartridges which are able to match the long-range performance of 7.62x51 with significantly less weight and recoil while being superior in penetration and terminal effectiveness to the 5.56x45 at any range, therefore enabling both existing rounds to be replaced by one.
Performance Requirements of a New Cartridge
4. To replace the 7.62x51 a new cartridge needs to achieve the following:
- to match the retained energy, vertex height and wind-drift performance of the 7.62mm M80 ball round at 1,000 metres
- to equal the barrier penetration performance of the 7.62mm M80 in terms of overall penetration of a range of media while maintaining its trajectory ("blind to barriers")
- to exhibit rapid and reliable yaw on impact with ballistic gel representing a body, ideally commencing within 50mm of penetration and completing bullet upset within 250mm
- compared with the M80, to reduce the weight to 80% (assuming similar materials) and to reduce the recoil energy in a similar rifle to 60%
5. To replace the 5.56x45 a new cartridge needs to achieve the following:
- to deliver a substantial improvement at all ranges over the 5.56mm M855 in barrier penetration and trajectory maintenance through barriers
- to deliver a substantial and reliable improvement in terminal effectiveness as measured in the size of the permanent channel created in ballistic gel tests within the 50-250 mm penetration zone, regardless of the bullet angle of yaw on impact
- compared with M855 ammunition, to limit the weight to 160% (assuming similar materials) and to limit the recoil energy in a similar rifle to 200%
Cartridge Design Requirements
6. The standard ball bullets used to achieve the performance requirements must comply with European legal interpretations of the Hague and Geneva Conventions governing military ammunition, i.e. they must be designed not to expand or fragment and any jacket must fully enclose the tip.
7. The standard ball bullets should be made of lead-free materials and be suitable for economical mass production.
8. The cartridge designs should be optimised for use in conventional military magazine-fed and belt-fed automatic weapons, so that existing gun designs can be adapted to use them.
9. The cartridge case design should be suitable for manufacture in a range of materials, including brass, steel and part-polymer.
General Observations
10. To achieve the weight and recoil reductions compared with 7.62mm M80 implies a lighter bullet to be fired at a lower muzzle velocity. To achieve this while matching the energy delivered by the M80 at 1,000 metres requires a bullet which loses velocity much more slowly than the M80. This requires a high ballistic coefficient which, given a lighter bullet, implies a calibre smaller than 7.62mm.
11. Comparisons of existing cartridges with the performance requirements listed above indicate that the optimum calibre will probably lie between 6.5mm and 7mm, with a muzzle energy of around 2,500 joules.
OUTLINE SPECIFICATION FOR A LIGHTWEIGHT HIGH-PERFORMANCE SMALL-ARMS CARTRIDGE
The problem
1. Combat experience in Afghanistan has revealed that 5.56x45 NATO ammunition has insufficient range for at least half of the small-arms engagements, and suffers from poor barrier penetration and unreliable terminal effectiveness even within its range.
2. Weapons chambered for the older 7.62x51 NATO ammunition are therefore seeing much more use, but while this ammunition is effective it is heavy and generates high recoil.
3. The aim is to design a cartridge or cartridges which are able to match the long-range performance of 7.62x51 with significantly less weight and recoil while being superior in penetration and terminal effectiveness to the 5.56x45 at any range, therefore enabling both existing rounds to be replaced by one.
Performance Requirements of a New Cartridge
4. To replace the 7.62x51 a new cartridge needs to achieve the following:
- to match the retained energy, vertex height and wind-drift performance of the 7.62mm M80 ball round at 1,000 metres
- to equal the barrier penetration performance of the 7.62mm M80 in terms of overall penetration of a range of media while maintaining its trajectory ("blind to barriers")
- to exhibit rapid and reliable yaw on impact with ballistic gel representing a body, ideally commencing within 50mm of penetration and completing bullet upset within 250mm
- compared with the M80, to reduce the weight to 80% (assuming similar materials) and to reduce the recoil energy in a similar rifle to 60%
5. To replace the 5.56x45 a new cartridge needs to achieve the following:
- to deliver a substantial improvement at all ranges over the 5.56mm M855 in barrier penetration and trajectory maintenance through barriers
- to deliver a substantial and reliable improvement in terminal effectiveness as measured in the size of the permanent channel created in ballistic gel tests within the 50-250 mm penetration zone, regardless of the bullet angle of yaw on impact
- compared with M855 ammunition, to limit the weight to 160% (assuming similar materials) and to limit the recoil energy in a similar rifle to 200%
Cartridge Design Requirements
6. The standard ball bullets used to achieve the performance requirements must comply with European legal interpretations of the Hague and Geneva Conventions governing military ammunition, i.e. they must be designed not to expand or fragment and any jacket must fully enclose the tip.
7. The standard ball bullets should be made of lead-free materials and be suitable for economical mass production.
8. The cartridge designs should be optimised for use in conventional military magazine-fed and belt-fed automatic weapons, so that existing gun designs can be adapted to use them.
9. The cartridge case design should be suitable for manufacture in a range of materials, including brass, steel and part-polymer.
General Observations
10. To achieve the weight and recoil reductions compared with 7.62mm M80 implies a lighter bullet to be fired at a lower muzzle velocity. To achieve this while matching the energy delivered by the M80 at 1,000 metres requires a bullet which loses velocity much more slowly than the M80. This requires a high ballistic coefficient which, given a lighter bullet, implies a calibre smaller than 7.62mm.
11. Comparisons of existing cartridges with the performance requirements listed above indicate that the optimum calibre will probably lie between 6.5mm and 7mm, with a muzzle energy of around 2,500 joules.