Steel case ammo has a long history. A great deal of WWII U. S. .30 Carbine and .45 ACP ammo was steel cased, and it worked just fine. Steel case .45 ammo was in use by the U. S. military into the 1950s. The Germans also used steel case 8mm Mauser and 9mm ammunition. The only problem with the WWII steel case .45 ammo (and I have fired many thousands of rounds of it) is that fired cases tend to stick in the chambers of my M1917. So I use only brass cases in the M1917. It's quite a bit stronger than brass, but corrosion can be a problem under some circumstances. Earlier in WWII, there was a case corrosion problem with it during the Pacific campaign, mainly because of the shipping containers. There was a crash program to recall it and re-package it in sealed shipping containers more immune to dampness and salt air.