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; 343 views.

From: Parnis


Was the 13.2mm Hotchkiss HMG cartridge significantly lower in power than the 12.7mm Browning HMG round?  I had always understood that they were almost identical.  But Michael Bussard's "Ammo Encylcopedia" (I have the 6th edition) says that the 13.2mm Hotchkiss had a 791 grain bullet moving at 2,210 feet per second for a muzzle energy of 8,578 ft/lbs.  The corresponding figures for 12.7mm Browning HMG are 720 grains at 2,810 fps for 12.600 ft/lbs.  Does Bussard have a bee in his bonnet, or is he on to something that others have been wrong about for decades?

BTW, if you have the 6th edition of this book, the relevant pages are 642 for 12.7mm Browning, and 711 for 13.2mm Hotchkiss.

This is my first post in a long time, so please let me know if I have put it in the wrong place or made some other mistake

  • Edited 18 September 2020 23:43  by  Parnis
In reply toRe: msg 1

From: autogun


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

From: Parnis


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.