.55 Boys
1937 · Royal Small Arms Factory · 1 firearm in catalog
Also known as: 13.9x99mmB, .55 inch Boys, .55 cal Boys
Cartridge specifications
| Bullet Diameter | 13.9 mm (0.547") |
| Neck Diameter | 15.6 mm (0.614") |
| Base Diameter | 20.4 mm (0.803") |
| Case Length | 99 mm (3.898") |
| Overall Length | 138 mm (5.433") |
| Typical Bullet Weight | 60 g (926 gr) |
| Typical Muzzle Velocity | 747 m/s (2451 fps) |
| Typical Muzzle Energy | 16740 J (12347 ft·lbf) |
| Primer Type | Large Rifle |
| Cartridge Type | Belted |
| Introduced | 1937 |
Firearms chambered in .55 Boys
- Boys Anti-Tank Rifle — Royal Small Arms Factory, Enfield · Sniper Rifle · 1937