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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons, particularly in larger calibres (12.7+mm).

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Power of 13.2mm Hotchkiss Cartridge   Small Arms <20mm

Started 18-Sep by Parnis; 345 views.
In reply toRe: msg 1
autogun

From: autogun

19-Sep

Welcome back! Yes, this is the right place.

Coincidentally I have recently been looking harder at the development of the 13.2 mm Hotchkiss, which was far more complicated than the usual "take one .50 BMG case and neck it out a bit" assumption. With thanks to French cartridge researcher Philippe Mention who did all the research.

The story started with a 12 x 87 round developed in 1901 - a Hotchkiss private development, somewhat hindered by the fact that the French Army couldn't see the point of it. Development was slow, and put on hold by WW1. It was picked up again after the War, resulting first in a 12.5 x 89. A complete redesign took place in 1921 resulting in a 13 x 96 round; further work saw this modified to 13.2 x 99 which was adopted as the Modele 1930. This has a close resemblance to the .50 BMG (although the shoulder and neck shapes are different), and fired a 48-52 g bullet (depending on type) at 790-810 m/s, giving a muzzle energy of around 16,000 J, compared with c. 16,200 J for the .50 BMG initially (around 18,000 J later).

Incidentally, the Modele 1935 loading, which had the case neck shortened to give an overall case length of 96 mm, had nothing to do with distinguishing the round from the Browning as is generally thought; it was due to changes to the bullet shape to reduce the barrel wear. 

Finally there was the German version, with the case length further reduced to 93 mm to take an HE bullet. However, this bullet was not the one from the MG 131, being somewhat longer.

The above pic shows the .50 BMG (M20 API-T) next to three 13.2 mm loadings: the 13.2 x 99 Mle 30, 13.2 x 96 Mle 35 and the 13.2 x 93 German

  • Edited 19 September 2020 22:29  by  autogun
Parnis

From: Parnis

19-Sep

Wow.  Thanks for your reply, Mr. Williams.  Like so many things I thought I knew something about, the reality was far more complex.  I would never have guessed the trail began in 1901!  I hope you learn enough to write about it to your satisfaction.

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