Fantastic answer, thank you.

Isn't it a retrograde step, design-wise, to have to remove the barrel for loading (and cocking) when, eg, various opening and closing breaches were in widespread use by then, such as gas-type turn breaches on butt reseroir airguns (and air canes?)?

Fair enough for a tinplate cheapie like the Diana mod 1, but not on a relatively expensive pistol/rifle like the Bussey, surely?

It's such a pain to have to remove the barrel for every shot, who would shoot for long?

Could it have been patent reasons that led Bussey to go with his novel plunger-cocking method in the end?