I did a two-part article on the Hollenbeck/Three-Barrel/Royal Gun Companies in The Double Gun Journal, Volume Thirteen, Issues 2 and 3, Summer and Autumn 2002.

There seem to be quite a few nameless three-barrel guns around that workers, etc. took in lieu of pay, or finished up on their own. Gun number 1746, a 12x12x.32-40 shown in my article is such a gun.