I thought of the Remington 100 also. I think the original Remington 100 was in .221 Fireball.
Side note: I remember there was some British spy novel that actually had a lot of correct information about guns in it that included the Remington as a super duper people killer hand gun. In another chapter it had info about a .375 H&H magnum rifle that made me want to get one of those too but I never did get either.
The thing looks a little like the Ruger Charger too although I hope the Charger would have better accuracy.