Robert,

You should have said you wanted a broader search...
Gunsmith's in the 1880 Census - 2,132. Those residing in New York - 160. Those residing in Buffalo - 3.

They were:
George T. Drywood
Buffalo, Erie, NY
68 Eagle
born abt 1859 England

Frank H Escherich
wife Barbara
Buffalo, Erie, NY
born abt 1840 Bohemia

James Lawler
wife Ellen
Buffalo, Erie, NY
204 West Tupper
born abt 1824 Ireland

937 residents in Buffalo listed their occupation as machinist. A lot of caveat's apply. Not every one was working for an arms maker.

Since you are local... There most likely was published a Buffalo City Directory. It simply has not been digitized on-line. When I was researching the Lefever "Time Board" photo, 95% of my hits came from the city directory. They often list not only occupation, but also employer. Also if you have the employer you can often find the employees who otherwise did not list their occupations in the directory.

Here is the sort of data you can gather from a city directory:
http://lefeverforum.informe.com/viewtopic.php?p=312&highlight=#312

http://lefeverforum.informe.com/viewtopic.php?t=84

Pete