Re: 6.5/300 Weatherby
Try Vhit N-160, H4350, OR H1000. This sounds like its going to be a screamer. With a 26" pipe, you will probably get around 3350 to 3400, maybe more, with the 139grn Scenar. If you go with a 30" tube, I am thinking 3450fps. Good luck, and let us know how she shoots.