Thanks, Drew that was interesting. Greener says, "wedges the barrels to the standing breech". Other systems more or less just hold the barrels down, which works out in practice. E.g. as the Parker and Winchester 21 are two of the best made and practically functional guns and don't wedge or pin the barrels at all, which shows the importance of execution and quality steel vs. design.

That's a nice gun from a maker I've never heard of! Would you consider posting more pictures of it so we could discuss and learn more about it?