.55 Boys | ||||||||||||
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Type | Anti-tank rifle cartridge | |||||||||||
Place of origin | United Kingdom | |||||||||||
Service history | ||||||||||||
In service | 1937–1945 | |||||||||||
Used by | United Kingdom Commonwealth of Nations Finland, et al. | |||||||||||
Wars | World War II Winter War Continuation War | |||||||||||
Production history | ||||||||||||
Designed | 1937 | |||||||||||
Manufacturer | Kynoch | |||||||||||
Specifications | ||||||||||||
Parent case | .50 BMG | |||||||||||
Case type | Belted, bottleneck | |||||||||||
Bullet diameter | 14.3 mm (.565 in) | |||||||||||
Neck diameter | 15.392 mm (.606 in) | |||||||||||
Shoulder diameter | 15.34 mm (.604 in) | |||||||||||
Base diameter | 20.168 mm (.794 in) | |||||||||||
Rim diameter | 20.244 mm (.797 in) | |||||||||||
Rim thickness | 2.44 mm (.096 in) | |||||||||||
Case length | 97.79 mm (3.85 in) | |||||||||||
Overall length | 133.43 mm (5.253 in) | |||||||||||
Ballistic performance | ||||||||||||
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Test barrel length: 914.4 mm (36 in) Source(s): Ammo Encyclopedia, 2nd Edition by Michael Bussard |
The .55 Boys (13.9×99mmB in metric) is an anti-tank cartridge used by the United Kingdom during World War II. It was designed for use with the Boys anti-tank rifle.