I edited out my attempt at a table, check out the one Semisane put in as it's the one I was trying to post.

The chart doesn't have BH209 but it weighs less than or similar to 777 2F, I don't have the exact figure at my finger tips but think it's around 70 grains by weight per 100 grains by volume, so weighing several volume charges as stated earlier is your best bet to find the safe weight to base your loads on.

Good luck and be safe.