.90 Cal. T4


I have a .90 Cal T4 that I would like some more info on. When were these in use? The headstamp is “CAL 90 T4 (quartermaster symbol)) 4430 - F A 1 W R”. What does the 4430-F A 1 W R mean? In ink on the head is “AMM LOT 130–8P-A” with a black band across the niddle od the head. What does the black band mean? On the side of the case in black ink is “HERC.NH.M2 HERC.LOT 4148-1939 CAL. .90 G T4 MV2700”

The projectile has an aliminium flat nose fuze cap. The body is black (appears to have been painted over a bright yellow) with “INERT” in white letters. Below this is a 23mm wide coppor driving band. Does the “INERT” mean just the projectile or the entire round. There is no other sign of the round being inert. It sounds like it is filled with a coarse granualar powder and the copper primer is not struck. The whole round is packed in a heavy cardboard tube.

Any information about this round or the entire series of .90 Cal. T4 ammunition would be appreciated.


This is a target practice round, the propellant is still in place.
The cartridge is a pre war experimental T4, there are also T1, T2 and T3, they are all different but have the same caliber.
About history and data the US-guys here certainly can tell more.


The .90 series was a programme which seemed to be intended to produce an aircraft gun, some time in the late 1930s-early 1940s (I have a brief history of the programme somewhere, but can’t lay hands on it). The gun designs were different as well as the ammo, but they all turned out too heavy and slow-firing, so were never used. Ammo for the T4 seems fairly common, the rest I’ve only seen photos of.