Well, the Track of the Wolf catalog says the G Goulcher lock was used in the 1840-1880 time period. (They sell a Davis copy of this lock).
The book AMERICAN GUN MAKERS shows a George Goulcher in New York but doesn't give dates but says, "Possibly made locks only".
Also, John Goulcher in Easton, Pa active before 1772-1777 and a Joseph Goulcher in Pa in 1841. It questions whether he is also Joseph Golcher who it says was active in Philadelphia, Pa and later on the Pacific Coast.
It also lists a George Golcher in New York, James Golcher in Philadelphia who died in 1805, James Golcher in Philadelphia "before and after 1833, John Golcher in New York during the percussion period, Joseph Golcher (I mentioned above), Manuel(or Emanuel) Golcher (also Goulcher) Philadelphia 1824-1830, and William Golcher in St.Paul, Minn., 1854 to 1870.
As you know, spellings for names in the 18th and 19th century were often changed for no apparent reason and this leads to the possibility of two slightly different names being the same person.