All those CZ rifles hav got overly inflated in price Especially like th FB and hornets 14-1500 range is just too much i spent just a little more and got a kimber of Oregon And yes I have built several 221s and 20 VT on a cz223 action they seem to work pretty darn good
I have ran some .20 Vartarg through my CZ 527 .223 mag and bottom metal but on my Howa Mini action. It fed ok and could probably feed good with some tweaking of the mag lips. Hoping it feeds perfectly in your 527. CZ 527 .221 Mags are hard to come by these days.