Chopped 41
Brass is the better material for cartridge cases. It is more ductile and forms a better gas seal in the chamber. Brass is also more corrosion resistant and has lower friction, important for semi-auto and fully automatic arms. Most brass cases can be reloaded several times. This gives once fired cases a value above their scrap value. Even as brass scrap the metal is priced by the pound where steel scrap is sold by the ton.
Steel cased ammunition was used by several of the belligerent powers in WW II. This was particularly true in Europe where copper, about 70% of cartridge brass, was in critically short supply. Even the US, with a string of huge copper mines in the west, resorted to steel cased ammo. However, only .45 auto steel cased ammo was released for use without restriction by the US Army. Carbine, .30-06 and .50 cal ammo were also manufactured but their use was limited. Much of US steel cased ammo was labeled FOR TRAINING ONLY or NOT TO BE SHIPPED OUTSIDE THE CONTINENTAL US. By late 1944 the US Army was convinced that the need for ammunition would not exceed the supply of cartridge brass and US military steel cased ammunition manufacture was discontinued.
After WW II the Soviet military continued to use steel cased ammunition. Many of the ammunition manufacturing plants that they set up in satellite states also manufactured steel cased ammunition. That is why much of the steel cased ammunition on the US market today was made in former communist block countries. When you could buy a SKS for $69.95 and get cheep, cold war surplus 7.62x39 ammo you could leave behind to rust away steel cased ammo got quite a few fans in the USA.
I heard one firearms instructor say "if you have a commie gun go ahead and shoot commie ammo in it."
Many perfer to shoot brass ammo and avoid concerns about lacquer or polymer coating build up or faster extractor wear.