So I've been collecting parts for a .223 rifle build for a while. The only component I'm missing is the barrel. The stock is a Manners T-5 channeled for a #7 contour barrel from another build that never happened. I'm at a loss as to what twist and length I want to go with. I might go varmint hunting once in a while but it will mostly be a range gun. I'd like to shoot a variety of bullet weights out to about 700yrds. I've read 90gr .223 rifles can only shoot 90gr bullets accurately. Is this true? What barrels are you guys using? Any insight is greatly appreciated.