M1 Submachine Gun (simplified Thompson variant, quickly replaced by the even simpler M2)
ah...that would be the M1A1, IIRC, Mike....and then the much simpler M3 and M3A1 Greasegun....
Military designations are such fun....
When someone says M4, are they talking a bout a 5.56mm carbine, or a Sherman tank?
And is a P-38 a 9mm pistol, or a fighter plane? OR a GI can opener?
Yes, depending on context
and there is at least one other Jap type 99 that I know of, the Aichi Type 99 dive bomber (known as the "Val" to US forces)
I'm sure there's more, we just have to find them...type 99 chopsticks? M1 Bootlace?