12 gauge, top of barrels says Hunter Arms, as far as grade no clue, this type of firearm is new to me. However the engraving seems very unique compared to others I've looked at on this site, plus others listed for L.C. Smith shotguns. Found many people looking for parts, that"s why I stated all serial #'s matched, nothing has been replaced. really good condition for 108 years old, really good!!!!