BP Conversion Sheet (revised December 2012)
777 is very energetic, and should not only be measured in a VOLUME measure, but the volume charge should also be reduced 15% in FFg and 20% in FFFg as compared to FFg Black Powder or Pyrodex RS by VOLUME for equal velocities. In other words you get more bang for your buck because not only do you use 15% less VOLUME, but it is also 23% less dense by WEIGHT.
100 grains VOLUME 777 FFg = approximately 77.7 grains WEIGHT 777 FFg ( +/- depending on storage, humidity, Lot #, and volume measure used. It could be anywhere from 73 to 78 grains weight in my experience.)
100 grains VOLUME FFg Black Powder (100 grains WEIGHT +/- 5 grains approx) = 85 grains VOLUME (66.04 grains WEIGHT) 777 FFg. This is where your more bang for the buck starts to come in.
100 grains WEIGHT FFG Black Powder = approximately 66.04 grains WEIGHT 777 FFG.
7000 grains WEIGHT in a pound. Basically "70" 100 grain VOLUME/WEIGHT charges in a pound of Black Powder FFg. A pound of 777 FFg should net you "105" 85 grain VOLUME (66.04 grain WEIGHT) but (100 gr VOLUME equivelant) charges as compared to black powder or Pyrodex RS.
So if you want to convert any of your Black Powder VOLUME/WEIGHT charges, always measure a sample of 5 - 10 charges of 777 FFg by VOLUME first, then reduce by 15% VOLUME , then use that average for your WEIGHT measurement.
I hope I didn't lose you, 777 and Blackhorn 209 are almost identical in energy by VOLUME, but they are definately more energetic than Black Powder, Pyrodex or other BP Substitutes. If I did lose you, please ask for clarification. Make sure that young man gets a VOLUME powder measure and reduce loads by 15% -20%.