Long range ar cartridge suggestions

Hey guys I'm getting ready to purchase my first ar and was wondering what caliber I should get. Currently I shoot 100-500 yards 0.5 moa with my bolt action and would love to transfer some of that capability to my ar purchase.

Right now I've selected .223 Wylde (rra predator pursuit). I currently reload 308 so odd ball calibres aren't a big issue as long as the brass shaping is namely a resized neck. Another one I considered was the 6mm ar.

Let me know your thoughts