Ruger .22 Standard Auto, before they were 'MK-anythings'.
Bought used at a Fayetteville Gun Show for 50 bucks about 1973. Owned it for about 30 years and I'm pretty sure a couple of pickup truck loads of ammo went through it - plinking, target shooting, small game hunting, etc.
I often took it on road trips with my Dad to go visit my Grandmother in South Central Texas. On her land and a neighboring ranch I had access to roam and take on Jackrabbits and Prairie Dogs. Jumping big Jackrabbits and taking them on the run was some of the best fun ever.
And, learned if I stayed inside the pickup truck, loaned to me on the neighboring ranch, the Prairie Dogs paid little attention to the ranch truck.... I could stay inside it, and the Prairie Dogs were in serious trouble even at 100 yds. using the truck door for a rest with that accurate Ruger.
I once brought a newly acquired Ruger 10/22 and tried out the then-new CCI Stinger ammo on distant dogs - they worked, but were much more affected by the constant wind there.
Both of those Rugers went away in trades. Good memories though.