At this moment it would have to be my 1940's era .32-20 Smith & Wesson M & P revolver, but I have put a down payment on a 1888 Commission Mauser that was made in 1891.
My oldest is a percussion Kentucky rifle .36 cal octigonal barrel half stock my granddad gave me. Probably dates from circa 1840's.
Oldest I shoot is a 1881 trapdoor carbine. Sweet shooter
Don't have many old ones left. Gave them to my family. Still have my 1926 Colt. S.A. 44. And my 1942 model 94 Win. 30-30 that I took my first buck with in 1953. I once owned a Model 94 Win. 38-55 T.D. serial # 312. Oh yeah, a S&W Prewar 22-32 Target & it's a good shooter.
The oldest gun in my inventory is a U.S. Model 1816 flintlock musket (Springfield Armory second variation - browned). The lockplate shows a date of 1826. A little before my time...
U.S. Model 1896 Krag Carbine. The ser.# says a feller carried it up some hill in Cuba. It'll still put 3rds in an inch at 100 yds.
The next oldest is my .44 HE 3rd model, ser. #29XXX. Late 1920s I think. It shoots great when I can see.
1903 Springfield brought back from WW I by my grandfather's uncle and then later sporterized (fixed 4x Lyman scope, new stock, barrel cut and re-crowned).