Would you say that there is likely to be any difference in potential accuracy between the 300 Winchester Magnum and the 300 Weatherby Magnum and the 300 Remington Ultra Magnum? If so which would tend to be most accurate and why? Let us assume initially that the rifle would be a 50# 1000 yard bench gun. Next a 9# big game sporter rifle. Which company makes the best bulk brass for the 300 Weatherby and for the 300 RUM? Thanks, Rufous.