12.7 x 81 (v/580)

Calibre specification

Metric (mm) Imperial (in)
Calibre 12.7 x 81 .5
Name:
Case Type: Rimless, bottlenecked
Bullet Diameter: 13.05
Case Length: 81.2
Rim Diameter: 18.30
Neck Diameter: 13.70
Shoulder Diameter:
Base Diameter: 18.37
Total Length: 107
Weight: 80.5 grammes
Primer: Berdan
Year Introduced: 1923
Also known as:
  • .50 Vickers-Armstrong
  • .5-inch Vickers Mark C
  • 12.7mm Patrone S.m.K. 755(e)
  • 12.7 x 81

Variants

In British and Commonwealth service, the variants used are those shown in the Table below.

Type Mark Charge Bullet Notes and acceptance tests
Ball 1z Cupro-nickel envelope, lead/antimony core and aluminium tip. Two cannelures. Secured by coning into forward cannelure and indenting into rearward. Obsolescent [As of 1945 publication]. Rimless case. Figures “469” on base.
2 142.5gr. Cordite 7/2 Weight 580gr. Coated steel envelope, lead/antimony core and aluminium tip. Slightly longer than Mk. 1. Mk. 2 obsolescent [As of 1945 publication]. Accuracy: 9-in. F. of M. at 500 yards.
2z 140gr. N.C.
Armour Piercing W.1 142gr. Cordite 7/2 Weight 580gr. Steel envelope coated with cupro-nickel, combined tip and sleeve of lead/antimony and hard steel core. Before 1934, “W” was omitted from base stampings. Accuracy: 12-in. F. of M. at 500 yards. Penetration: 70 per cent., 18mm. Armour Plate at 100 yards.
W.1z 140gr. N.C.
Semi-Armour Piercing F.1 142gr. Cordite 7/2 Weight 580gr. Coated steel envelope, lead/antimony sleeve and steel core. Accuracy: 12-in. F. of M. at 500 yards. Penetration: 70 per cent., 15 mm. Armour Plate at 100 yards.
F.1z 140gr. N.C.
S.A.P./Tracer F.G.1z 140gr. N.C. Weight 542gr. Similar to F. Mk. 1, except that core is recessed to take 6 gr. S.R.368 (tracing) and 6 gr. S.R.370 (priming). Base closed by brass washer with envelope turned over on to it. Accuracy: 12-in. F. of M. at 500 yards. Penetation: 70 per cent., 15 mm. Armour Plate at 100 yards. Tracing: 85 per cent. must trace to 100 yards.
F.G.2z 140gr. N.C. Weight 549gr. No information re make-up of filling. Accuracy: As for F.G.1z.  Penetration: As for F.G.1z. Tracing: Dark Ignition, 85 per cent. must trace to 800 yards after 100 ± 40 yards.
Incendiary B.1z 142gr. N.C. Weight 562gr. Make-up similar to .303 B, Mk. 7. Filling 28gr. S.R.365 and 2gr. Q.F. composition. Accuracy:  18-in. F. of M. at 500 yards. Performance: 17/20 good flashes on impact.
Proof Q.1 140gr. Cordite 3½ Ball 1z Bullet. Weight 580gr. Cartridge coppered all over. Gives pressure of 17/29 tons per sq.in.
Dummy U.1 Nil Weight 590gr. Copper alloy or coated steel envelope with lead/antimony core and aluminium tip. Non-explosive. Wooden distance piece under bullet. Chromium-plated brass, or white metal case.
Drill D.1 Nil Weight 370gr. Cupro-nickel envelope and aluminium core. Non-explosive. Wooden distance piece. Case of chromium-plated brass with 3 longitudinal grooves in body. Empty cap chamber.

Countries using this calibre

Australia
Canada
United Kingdom

Sources: