Must be one of those very rare Winchester lever-action flintlocks
Seriously, Winchester wasn't around in 1776.
The first Win. lever action was the model 1866 (.44 RF)
The Model 1876 is the long-action version of the famous Model '73.
Of course, Winchester has made a ton of wackey M94 commemoratives.
I wonder if one of them was some sort of 1776 commemorative?
Yep! found a couple of "USA Bicentennial 1976" commemoratives on GunsAmerica.