"I swear it looks like its aluminum cased."
If it's US military, it's going to be headstamped EC 43.
In 1942 the US faced big time shortages of copper, the primary material used to make brass for cases, so the military approved loading .45 ACP ammo in steel cases.
As far as I know, the only plant to make them was Evanville Chrysler Ordnance Plant, and virtually all were made in 1943 (although there have been reports of some EC 44 steel case ammo).
This ammo was never intended to be sent to combat troops -- it was intended for stateside training purposes only.
The copper shortage also caused the US mint to switch from copper pennies to steel for 1943, as well.