Gentlemen, I beg to differ.
I may not match your expertise in 18th century arms but over more than 35 years I have collected hundreds of 14th-17th century guns, related items and Gothic and Renaissance iron work, let alone completely dismantled many hundreds of 18th-19th items and passed expert opinions on them.
I cannot see any argument why the iron parts and the stock (the original polish was probably taken off the latter) should be fake. Who on earth should do that - and why? Imagine the price you can possibly get ...
Best,
Michael