M139 gun ammo box

My understanding is that this ammo is for Hispano-Suiza HS.820 20 mm autocannon which probably goes through 25 cartridges on a battlefield in a matter of a couple of minutes. So why to pack only 25 rounds, why not 100? Also, how old is this box?

1 Like

Weight Limitations on what one or two soldiers can carry…25 rounds 20mm HS ammo probably weighs as much as 100 rounds of .50 BMG… Especially the Solid Shot AP.

Also, 25 rounds of HEIT ( High Explosive Incendiary Tracer) will make a lesser Explosion if hit than 100 rounds of same…

And also the sheer size of a 100 round Tin ( “ManPac”).

These days with OH&S regulations, Stress Induced Injuries etc, all armies have become Wussy…Not like during WW II, when Chests of rifle ammo were 1200-1500 rounds, and Mortar Bombs (3"") were packed in six per Crate; ( barely liftable by a single, fit soldier…usually required two to transport any distance.)

Doc AV

Nice ammo box, especially with the experimental XM599 Cartridge, 20mm High Explosive Incendiary Tracer (HEIT XM599) marking.


1 Like

And interestingly having been made by Hispano suiza!

Brian, you got data on this projectile?


Unfortunately I do not have any information other than the XM listing.


Vlad, this is a M528 box and it was US standard for these cartridges. It was packed in wirebounded pairs (50 rounds).

The XM599 designation was assigned August 1966, used at least until 1969, and by 1971 standarized as the M599 (projectile is yellow painted with red T’s). The M601 was already standarized by 1968 (projectile is black painted with orange T’s and red tip).

Also, there are variations of this box with markings indicating all cartridges by Diehl, H-S or Rheinmetall.

For those who are interested here is a link for an excellent display and description of sectioned 20x139mm HS 820 (Oerlikon KAD) cartridges: bocn.co.uk/vbforum/threads/8 … -RH202-Gun

Vlad, that is the nicest box I have seen. Mine are all repacks.


1 Like

The M139 gun (HS 820) was a rare offshore procurement for the M114A2 carriers and in retrospective it is considered a mistaken decision. After a few years in service this was solved with the adoption of the M242 Bushmaster.

I’ve got the exact same box, same markings just different lot numbers!

1 Like