i'm looking at Ballistic Advantage barrels on armorally.com to finish my first big boy AR build. From what I have read, the Hanson profile barrels are supposed to be somewhat lightweight. The 18 inch Hanson is 57 ounces and the 18 inch heavy barrel is 52.5 ounces according to the arm or ally website? What am I missing here? Are the 308 barrels different in some way?