[Lone Sentry: Japanese Model 99 Machine Gun, WWII Tactical and Technical Trends]
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"Japanese Model 99 MG" from Tactical and Technical Trends

This U.S. intelligence report on the Japanese Model 99 machine gun was originally printed in Tactical and Technical Trends, No. 35, October 7, 1943.

[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


The Japanese Model 99 (1939) 7.7-mm caliber light machine gun, a weapon of relatively recent development, (see accompanying sketch) is very similar to the Model 96 (1936) 6.5-mm gun. Nearly all variations result from the change to the larger caliber. The general characteristics as reported by the Aberdeen Proving Grounds, follow:

Weight w/o magazine    20 lb
Overall length42 in
Weight of barrel6 lb
Length of barrel21 3/4 in
Rifling4 lands and grooves (left hand uniform twist)
*Rate of fire800 rpm (automatic fire only)
*Muzzle velocity2,300 fps
Front sightFlat post
Rear sightDrum type with click adjustment for windage and elevation.

[Japanese 7.7-mm Machine Gun, Model 99]

An adjustment for headspace is incorporated in the barrel retaining bolt. A tapered groove is cut into the barrel near the breech and a corresponding tapered surface is milled into one side of the locking bolt. As the locking bolt is drawn from left to right by means of a large hexagonal nut which pivots on the outer end of the bolt lock and screws on to a fixed collar, the barrel is forced to the rear, thereby decreasing headspace. The bolt lock nut is marked from 1 to 8. On the forward face of the receiver, to which the barrel is held in close contact, a washer is provided so that the replacement can be made as excessive wear occurs. The washer is about 1/16 inch in thickness.

An adjustable rear monopod is provided which is mounted in a recess in an extension of the butt plate. A flash hider is screwed onto the barrel in the conventional manner rather than attached by a bayonet-type lock as is found on the Model 96. The staggered box-type magazine is longer and slightly less curved than the one used for the Model 96. The safety lever on the Model 99 is located on the left side while on the Model 96 it is on the right. Ammunition for the Model 99 light machine gun is rimless.

*Not checked by Proving Ground Test.


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