PSA has the CMMG kits in stock and on sale for $200. Kit includes three 25 round mags. IMO everyone with an AR needs one of these or a dedicated 22LR upper.Try Gunrunner Arms in Junction City. I know it's a little drive. But they often have what I can't find elsewhere..
If not.. if you have a 556 AR, it would be worth getting the CMMG Bravo 22LR BCG adaptor. Mags are abundant and I can run all sorts of ammo through it and never has jammed.