Very litte new at any rate - some muzzleloaders have had them - pistol gripped rifles, of course. That limits countries of origin and period, of course.

I'm sure I saw an English Sporting rifle of the 1850-60 period with that 'chin strap'- raised panel around the crip cap. Too, they were common on some plains rifles around the bottom of the cheek piece and behind the tangs.

Quite normal on Sharps as well, forward from the bottom of the action - that would put them 1874 through 1885 anyway.

This in no way, detracts from their form and good looks.