I must admit I was confused about the steel cased ammo until recently. Almost every indoor range I visit does not allow it and I had believed it was because the bullet is steel and not lead. As it turns out I was wrong in that belief. Most of the steel jacketed bullets are Russian or Chinese in origin. The core of the bullet is lead covered by a thin amount of steel and then flashed with copper to avoid rusting. I found this nifty cut away on the web which shows the lead and steel casing.
The reasons I see given for not allowing the ammo is it has a tendency to ricochet based on the steel coating. I actually can see how that would be so if the steel hits a hard object like the backstop it has more potential for ricochet than the more malleable copper jacket or lead bullet. Several people say the steel case can ruin the barrel of the gun. I suppose that is another reason why the very thin layer of copper is applied, but don’t know enough about it yet to be able to say if it would harm the firearm over time or not.
One thing is for sure, the steel cased and steel jacketed bullet ammo are certainly less expensive than their copper and lead counterparts. However since my local range does not allow it I don’t see a benefit to purchasing something I am asked not to shoot. With at least the potential for damage to the barrel I think I’ll take a pass, even if it is a steel. 😉