Thompson/Center Renegade. They were made in .50 and .54 caliber from the mid 1970's to about ten years ago. One of the only American made rifles in the semi-replica realm. It doesn't really represent any particular historical rifle. These are very, very well made, very accurate, and will accept a good stiff hunting load. Accurate with either the traditional patched round ball or an elongated bullet. T/C introduced their "Maxi Ball" with this rifle, and the very similar, but brass mounted "Hawken" (which is anything but).
Not sure what these are worth these days. Probably not much. Check Gun Broker for completed sales. I bet you would be lucky to get $500 for it.
Here is my "Hawken", essentially the same rifle, just fancier. One of the best hunting rifles I own.
