I won't bore you with a long story, but back in the 70s, my father bought a Ruger Single Six .22 for coon hunting. I grew up in very rural circumstances when I was young. 2AM on a warm Michigan night, the challenge of hitting a ball of fur 80ft up in tree moving in the wind while a gaggle of coon hounds howled was considered sport.
I opened a drawer in my dad's fly fishing cabinet today, and spotted the box below. I recalled immediately what it was. The Ruger came with this .22 WMR (Winchester Magnum) cylinder. I doubt it was used more than a few times, before being put away.
A) Interesting caliber that actually did serve a purpose.
B) Fun finding an object that I have probably not touched in 40+ years in excellent condition.
C) Note the other conversion options! Interesting stuff.