Thin nickel plate.

I would generally advise against trying to bring this shotgun to "shooting condition" unless you stick to black powder shells. Cast iron frame and mostly unhardened steel working bits except for hammer, trigger,etc. IIRC this design is pre-smokeless powder era.

Still, IF you don't spend any more than you absolutely have to, AND you've nothing better to do, have at it! It'll build experience, if nothing else.

Dang, I can't recall the name...American Something, Something? let's see:

Crescent Arms
Iver Johnson Gun and Cycle
Lefever
Marlin
Champion
ETC., ETC.

Give me a while, or surf some, this action is fairly scarce anymore, mostly because the rest wore slap out long, long ago!