Frank:
Thanks for sharing photos of your William Gardner rifle. Attached are some photos of two full stock Wm. Gardner rifles. As you can see, both have mule ear locks which Gardner appears to have favored. The top rifle started life as a pill lock but was later converted for use with percussion caps. It has a 34 1/2" barrel and is a .32 cal. The bottom rifle is a .48 cal. with a 38 1/4" barrel.
There certainly are similarities in the stock style and design of your gun, and the example Majorjoel provided and the two I have listed.
A couple of years ago I was able to find copies of his obituary. He was born in Canandaigua, NY on Sept. 25, 1793 and died Feb. 23, 1882. He moved to Geneva, NY in 1815, was married in 1817 and resided on Pulteney St. The obituary also states that about 18 years prior to his death (1864) he went blind, which of course, ended his career.
I also located a notice Gardner submitted to the Geneva Gazette, June 14, 1837 in which burglars broke into Gardner's gun shop stealing "... an old double-barrel gun, one old rifle, one new rifle barrel ... a quantity of gun-smith tools.."
The NYS Firearm Trade, Vol. 2, (Swinney/Rowe) have other examples of Gardner's work.