So for my next AR I want a longer barreled varmint type build. Probably a 20-24 inch barrel, Magpul PRS stock, bipod, and a good scope. You can all guess where Im going with this lol. It ill be the big brother to my other 16" carbine setup. Anyhoo, Im looking to shoot out to probably around 500-600 meters. Do you think Id be ok using a barrel set up for use with higher powered 5.56 and/ or .223 rounds or should I go for something bigger like a 7.62x51/ .308 or something else? What am I using it for? Dunno, range gun, fun, the ever present zombie threat? who knows why not lol.