I have 2 new barrels in 6mm with and 8 twist. One is .236 dia. and one is 237 dia. I plan on shooting 600 and 1000 yards.both barrels are 28 inches in length.I want to have 1 chambered in 6mmbr and one either 6brx or 6x47 what would be the best bullets for either barrel,also what barrel would be best for which cal. thanks for any help, Rudy