As the title states, I need help deciding on the heaviest bullet I can run out of my 1-in-7, 18" .223 wylde AR. I will be shooting a team match in two months with targets out to 600 yards and I'll be the gas gunner. What I'm needing as far as guidance is to know, how heavy a bullet can I run with full velocity at mag length (Which I don't have those numbers with me but I'd assume not a ton further than 2.26" SAAMI)? I've been looking in the 69g range but I know my twist can get me a little more. So if you guys have some bullet suggestions or just some advice on where to settle I'd love to hear it. Thank you!