I cant tell from the OPs pics if the receiver is brass or steel, the majority of 1866 were brass receivered but I believe there is a steel receiver variant which is a bit rarer.
I also think this a Winchester, but which model I'm uncertain, short of model numbers, caliber marking on the rifle, a little more easily obtained info on this rifle could help determine which it is, e.g., measure the length of the barrel, measure the bore size as close as possible to help determine the caliber.