G. Goulcher was (probably) a third generation gun maker that was most noted for his locks which were standard hardware store stock in the mid/late 1800's.
Because of that, it really gives no clue as to where or by whom the rifle was made. Probably hundreds if not thousands of rifles in the mid to late 1800's had G. Goulcher locks on them (along with Leman locks which were every bit as popular).
Your best bet of at least nailing down an area or region where the rifle might have been made is by posting up some pictures.
Likewise the barrel markings are possibly from the supplier or barrel maker and may or may not have anything to do with who built the rifle or where (or even when for that matter).
