My 12 ga is English half stock inspired and utilizes an original buttplate, likely from an old double, that I picked up at a gunshow many years ago. Been told by several family members to wait till Christmas before getting a camera. Hope to learn to be able to post pictures soon. If JP Becks are pleasant to shoot I would guess the Dickert Rifles and a few other earrly rifles are also. Heavy large buttplates absorb recoil and also help to counterbalance the heavy long barrels of a long rifle. The slimmer buttplates of later years tended to be more curved also. The pointed curved buttplates of the some of the plains rifles, designed to be shot off the upper arm were in my opinion invented by the Marquis de Sade.
DP