That would be the Purdey double underbolt patent of 1863.

It was originally paired with the Purdey thumbhole underlever sitting inside a bifurcated trigger guard. Purdey then almost immediately formed an agreement with W&C Scott to use their spindle toplever opening system, in exchange for letting the latter use the new bolting system.

Last edited by Kip; 01/02/23 07:28 PM. Reason: Additional content