su37,
This is just my opinion from my experience with VVN170.
VVN165 is in the same burn rate as RL22, VVN170 is much slower than RL25 a huge gap making it closer to 50BMG powder's like VihtaVuori's 20N29. much too slow of a burn rate powder for a 264win mag even with the heaviest bullets,
try some VVN165 or IMR7828.
UB