BP versus 777

[SIGP2101]

I am confused and need clarification
My .44 Pieta Navy 1851 manual book states that it will take between 12-15 grains of BP. Hodgdon on their web site indicates 20-25 grains of BP.
To make things more complex I want to substitute BP with Hodgdon 777. How should I proceed? What is the safest method of building max loads for BP revolver uysing 777?

 

[d.bala]

I have 2. 44 black powder revolvers and load each one with 30 grains triple seven. also make sure you're using triple F powder in your revolver also note both my revolvers are steel frame and you might want to reduce your load for a brass frame as they stretch. I believe it is very hard to get a load that will overpower the pistol using black powder. My determining factor for using 30 grains was what gave my guns the best grouping.

 

[Dantforth]

If you want to stay with the 20 - 25 grain B/P load suggested by Hodgdon then use the same volume of T7. The T7 load will weigh less than the B/P load but will be safe at this level. All experts say that when substituting T7 for B/P you use the same volume as the B/P load...not weight. In my M/L a 90 grain load of B/P comes out to about 60 of T7....but they are the same volume.