I’m thinking of building an AR in .223 to bench shoot out to 600 and I’m looking for some opinions on barrel length/twist rate. I’ll be shooting 68-80 gr bullets and I like a heavy gun for the bench. I’m looking at maybe a 24” SS bull from Model 1 with a 1-8 rate, a 20" White oaks .223 Varmint barrel with a 1-7 twist or the White oaks 26”Match rifle barrel in 1-8 twist. If I wanted to stay in the 300 dollar range what would be a good choice for the most accurate AR?