M7 Auxiliary Grenade Cartridges


A number of people I have talked to have seen these cartridges before but didn’t recognize them for what they are. They are the M7 Auxiliary Grenade Cartridges. They were used to extend the range of rifle grenades launched from M1903 Rifles, M1 Rifles and M1 Carbines, although there was a warning that they were only for emergency use with the M1 Carbines. They were not to be shoulder fired with any rifle.

One was placed in the open end of the grenade launcher with the red disc pointing in the direction of the rear sight of the rifle before the grenade was placed on the launcher. When fired, the hot gases from the normal grenade cartridge in the chamber of the rifle would ignite the charge of the auxiliary cartridge and provide additional propelling power to the grenade.

They came packed in a small, unmarked 5-round box which was in a moisture and vapor proof sealed envelope that was marked for the contents. The envelopes were included in two of the three different types of grenade cartridge assortments that came in small “spam cans”.

M7 aux grenade cartridge


Thanks for showing that chart for ranges. It sounds like using the carbine with grenades and the booster would be quite the adventure! I note the differences in ranges for some applications between the M1903 and M1 rifles. Assuming the same launcher and cartridge, why the difference?



Dave – I noticed that and wondered about it myself. The M1903 and the M1 used different grenade launchers and the differences might be enough to cause that, don’t know!


Are these auxiliary cartridges ever found made of brass? Those I’ve seen have all been steel. Jack


Jack – The Ordnance Dept. drawing shows both brass and steel as case materials, but I, like you, have never seen one in brass


Phil: Thanks for the response and the drawing. Jack


For whatever it is worth I have a copper-washed steel unloaded case. No mouth crimp top wad or powder.


Thanks for this post, I have always wondered what this thing was since I got mine. I couldn’t find a obvious primer, and thought of taking this out of my collection. I’m glad I didn’t.