I have a LC Smith 12 gauge shotgun serial number 338xxx (which I believe dates it to 1912). It has 00 stamped below the serial number, and "steel" stamped on the bottom of each barrel. I believe that means it has armor steel barrels. Is that correct?

Also, do you know whether this gun (if original) would have 2 3/4" chambers?

I'm considering whether to fire modern shells (low brass target loads) in this gun. Is that a good idea? What about modern high brass (buckshot etc)?

Thank you for your help.