Well, topic WAS best RIMFIRE shots, so I would offer 2.
Savage 93 heavy barrel in .17 HMR. On the 100 yd line at my range. Slow afternoon- other shooters are mainly running 6mm benchrest guns.
Most of them are pretty cool folks- but was was a royal PITA. Kept referring to the .17 HMR as a "toy", advice to get a REAL rifle, etc. Until we walked downrange to get targets.
Had been a perfect afternoon- winds were steady 12 o'clock to 6 o'clock, light was excellent. Mr. Helpful just had to come over and snoop at my target as I pulled them. 4 ea 5 shot groups. 2 of the 4 had touching holes. The other 2 were just a hair bigger, but around .32 inches.
His mouth fell open. Concealing my glee, calmly said "Shoots pretty well for a toy. How'd you do?"
Episode #2- 20+ yrs ago, youngest son (age 12) and I had taken a few days in the mountains of SW VA, deer hunting. We had not seen anything that morning- had returned to cabin for lunch, and decided to walk up to road to the top of the knob, and glass the valley for anything moving.
Walking out to the road, we flushed a grouse from the side of the driveway. Carrying a Ruger Standard 22LR. Bird was about 25 feet up, I drew, fired 1 shot, bird hit the ground deader than a doornail, within inches of his takeoff point. Shot thru the head.
Son standing about 10 ft away, looking at me in wonder. "Hey pop- that was REALLY good!" Me- dead calm voice "Hang on son, let's see if there is another one in there."