| 12.7×81mm | ||||||||
|---|---|---|---|---|---|---|---|---|
 From top to bottom: ball, armor piercing, tracer, high explosive tracer, armor piercing high explosive tracer. | ||||||||
| Type | Heavy Machine Gun | |||||||
| Place of origin | UK | |||||||
| Production history | ||||||||
| Designed | 1923 | |||||||
| Specifications | ||||||||
| Parent case | Vickers .5V/580 | |||||||
| Case type | Semi-rimmed, bottlenecked | |||||||
| Bullet diameter | 13.05 mm (0.514 in) | |||||||
| Neck diameter | 13.80 mm (0.543 in) | |||||||
| Base diameter | 18.32 mm (0.721 in) | |||||||
| Rim diameter | 19.55 mm (0.770 in) | |||||||
| Case length | 81.2 mm (3.20 in) | |||||||
| Overall length | 107.2 mm (4.22 in) | |||||||
| Primer type | Berdan | |||||||
| Ballistic performance | ||||||||
| ||||||||
The 12.7×81mmSR cartridge was created by Vickers as an export variant of the cartridge developed for the Vickers .50 machine gun. The major changes were to modify the case from rimless to Semi-Rimmed and reduce the bullet weight from 580 gr (38 g) to 565 gr (36.6 g).[1]
- ^ ".5 Vickers Mk I Rimless". Municion Org. Retrieved 2024-09-29.