With the ever rising ammo prices, have many of you(us) picked a pistol-cal upper or adapter for your AR?

AR uppers in 9mm and 22 are great for cost effective trigger time without spending a fortune or depleting your SHTF ammo stash.

I bought an AR-22. Looks and feels like one of my AR-15s, but a lot cheaper to shoot. I was contemplating the CMMG kit, but I liked the rifle so much I couldn't resist.