We want to put a 300 BO barrel on a ar for sub use. The rail is 1 and 1/8 ID for 15 inches. I originally thought a 14 inch barrel with pistol gas tube would work good. After reading Lloyds thread on his 300 and others input I realized my approach was short on actual sub barrel operation. I will pin an extension on to the barrel to be legal. What would the recommended barrel length, twist and gas tube length be for sub shooting. I assume the possibility would be there to shoot super sonic if so desired. One good thing is short barrels are cheaper! At this barrel length is the accuracy better between cheap barrel vs short top of the line barrel? Your in put will be thoughtfully ingested and pondered upon!