Hard to say. Goex has been putting out a very uniform powder for cartridge rifles but with revolvers, single shot pistols and caplock rifles Ive used, the Swiss has been both denser and more powerful. Ie- a given measure will throw a heavier charge of Swiss than goex. When I actually weigh the powder charges to get the same grain weight of swiss and goex, the swiss still produces more velocity.
The lots of pyrodex P Ive used have been comparable to swiss -sometimes producing a bit more velocity and sometimes less. I have used pyrodex as much as 25 years old and found that can to be more like goex and and this is also suggested by data published at the time. Or heck, It could come from the age of the pyrodex.
The 777 is pistol grade. It works well with slightly reduced charges so long as they are not compressed. If there is mouch compression upon seating, the velocities become erratic.