.30 Carbine M6 grenade propelling cartridge - less known use


To my own surprise and after having looked for so long into all sort of large cal. auto guns I came across the T13 charging device of M38 cal. .60 and M39 20mm aircraft guns (+ related predecessors with T numbers).

The somewhat unusual charger used a revolver drum (actually the related guns were revolver cannons too) which is chambered for 8 EA cal. 30 (Carbine) M6 grenade launching cartridges. I thought I show the system here as it is a quite unusual approach (from my view).

charger cylinder-



Very interesting. I had never seen or heard this. Many thanks!



Very interesting. So there would’ve been a way to fire these from inside the cockpit?

I’d always wondered how they’d extract dud rounds mid-air, I’d just assumed there’d be an electrical system set up for it. Now I know better, thanks.


Lots of different recharge systems for aircraft cannons. Some are electrical like the 7.62 miniguns on the AC-47s I worked with in 1969/70. Others like the GAU 8 gunpod use a large bottle of compressed air mounted at the rear of the pod behind the gun.

This is a whole area for study. My vague memory is there are others which are cartridge activated but I thought they were purpose built activation cartridges like ejection seats, canopy ejection systems, fire suppression bottles, pylon ejection and similar systems. It never occurred to me that that a carbine blank would be used. Most activation cartridges are specially made and carefully managed since very few are actually used, but there is also a danger that they will age and not function when limited. There is a very comprehensive system to track the make sure they will reach their design live. None of this manufacturing controls and long term testing would apply to normal issue M6 grenade launching blanks. That is why I am surprised that standard issued blanks were used in these guns.



Lew, this could be the reason why there are 8 EA of them?

Thinking of more modern guns there are 1 (30mm DEFA + 30mm GSh-301) to if I remember correctly max. 3 (mainly Soviet systems using the PPL cartridge) CADs installed.

As Lew said there are several systems to cycle an aircraft gun in mid air:

  • electrical (if I remember correctly electro-magnetic systems)
  • compressed air (from pressurized gas containers)
  • CADs (working with propellants)

The CADs then are to be devided into:

  • electrical primers
  • mechanical primers


Here the device (designated M8A1 now) in a photo.
Actually this makes me wonder now if the device was replaced by something in later used weapons as the M6 grenade blank obviously was not made into the 1980s (at least) when the M39 guns were still in air (like in F-5s).
Anybody to tell? Unfortunately I have no late manual on the M39 gun.


The lack of normal CAD control could be the reason for 8. It could also be the reason for the revolver mechanism to cycle past a misfire. I believe the the number of carts was/is driven by both the functioning reliability of the weapon, the reliability of the ammo and the usage profile of the gun (lots of quick bursts vs fewer and longer bursts) as well as the total ammo capacity.


PS: The USAF Museum
1100 Spaatz Street
Wright-Patterson AFB OH 45433


Would likely have this information and could give you the answer on whether this was a standard installation or was replaced.