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ARMAG

Search matches names, aliases and the text of every page. An arm found by its service designation is found by its alias, not its title.

.50 BMG

Introduced 1921Winchester Repeating Arms Company and Frankford Arsenal

Also known as 12.7×99mm NATO, .50 Browning Machine Gun — the same cartridge under different names, all of which find this page.

Dimensions and pressure

Generated from the schema, like every specification table on this site, so a figure recorded on this entry cannot be missing from the table.

Identity
Designed by
Winchester Repeating Arms Company and Frankford Arsenal
Introduced
1921
Production
not recorded
Standards body
No standards body
Case type
Rimless
Case shape
Bottleneck
Dimensions
Bullet diameter
12.98 mm0.5110 inestimatedsource

C.I.P. does not list 12.7×99mm and the NATO standard is not free, so this is the uncited infobox figure of the article named, converted from inches. It is a lead, not a standard.

Bore diameter
not recorded
Case length
99.31 mm3.910 inestimatedsource

C.I.P. does not list 12.7×99mm and the NATO standard is not free, so this is the uncited infobox figure of the article named, converted from inches. It is a lead, not a standard.

Overall length
138.4 mm5.450 inestimatedsource

C.I.P. does not list 12.7×99mm and the NATO standard is not free, so this is the uncited infobox figure of the article named, converted from inches. It is a lead, not a standard.

Rim diameter
20.42 mm0.8039 inestimatedsource

C.I.P. does not list 12.7×99mm and the NATO standard is not free, so this is the uncited infobox figure of the article named, converted from inches. It is a lead, not a standard.

Neck diameter
14.22 mm0.5598 inestimatedsource

C.I.P. does not list 12.7×99mm and the NATO standard is not free, so this is the uncited infobox figure of the article named, converted from inches. It is a lead, not a standard.

Base diameter
20.42 mm0.8039 inestimatedsource

C.I.P. does not list 12.7×99mm and the NATO standard is not free, so this is the uncited infobox figure of the article named, converted from inches. It is a lead, not a standard.

Pressure
Maximum pressure
not recorded
Pressure standard
not recorded

SAAMI and C.I.P. measure pressure differently and their figures are not interchangeable, which is why the body is always named beside the figure.

Loads

No load data recorded yet. Without a sourced bullet mass and velocity there is nothing honest to compute, so the ballistic figures on pages that chamber this cartridge stay blank rather than being estimated into existence.

Chambered in

Computed from every entry that lists this cartridge. Nothing here is hand-maintained.

Gallery

A .50 BMG cartridge on orange graph paper, a long bottlenecked case with a white-tipped bullet.

Image credit

Title
File:Cartridge .50 BMG DAG.jpg
Author
Grasyl(attribution required)
Licence
CC BY-SA 4.0
Source
https://commons.wikimedia.org/wiki/File:Cartridge_.50_BMG_DAG.jpg
A .50 BMG round on graph paper. The white tip marks it as a tracer or incendiary loading rather than ball.

Detail

John Browning scaled his .30-06 up by a factor of roughly four in 1918, after watching German anti-tank rifles and the first armoured aircraft, and the result has outlasted every vehicle it was designed to defeat. A 45 g bullet leaving a metre-long barrel at more than 900 m/s carries about 18,000 joules — an order of magnitude past a rifle cartridge, which is why the arms that fire it weigh what they weigh.

It is also the clearest case on this site of a cartridge whose specification is not public. C.I.P. does not list it. The NATO standard costs money. SAAMI publishes a drawing that cannot be redistributed. Every dimension below is therefore the encyclopedia’s figure, labelled as an estimate, and no load row appears at all — the freely available velocity tables are handloading data from commercial reloading sites, which is neither a standard nor something this site records.

References

  1. .50 BMG · 1364906082 · read 2026-08-31

Last verified 2026-08-31 · review status: agent-populated