Is it possible to shoot 500+ yards with a .650 barrel ? My .300 Win Mag, shoots great with it's stock .655" barrel, best group being a 0.66" 3 shot group, with a warm barrel. Just wondering if it can be accurate further out, or if I do need to replace the barrel. Been talking to Ed Harren about doing a rebarrel to a #6 contour 26" Shilen. Just hate to change it while it is shooting so good.