Yes I cast 22 caliber bullets for one of my ar-15s. It has a 1-9" twist barrel. As GPMan said smallbore fast twist rates can be daunting.
I have a custom mold made by NOE from over on cast boolits but it is a copy of this mold: http://www.midwayusa.com/product/100...oint-gas-check
I load it over 19 grains of reloader 15 and have used 19 grains of H4895 too.
One of these load gave me just over 2100 FPS, but I forget which one.
Great accuracy from both loads with no leading, using WDWW's, sized .225"