One of my pals has turned up a very unusual double rifle, in like-new condition apparently. It was made by George Gibbs of Bristol (better known for falling blocks) in about 1880 I reckon. The calibre seems to be .360 No. 3, firing a 215 grain bullet propelled by 35 grains of powder, so not very powerful at all.

It has a Jones underlever but is hammerless, with his own design of action. The tumblers are pivoted on a trigger plate section inside the triggerguard. I have never seen anything like it, but have found one reference to a shotgun with this type of hammerless mechanism.

If someone can send me a PM then I can forward a photo for posting.