[dandak]

I gave up on black powder years ago. Use pyrodex exclusively in all my black powder guns (levers, cap and balls, trapdoors). For my 3rd gen 1851 navy I set a black powder VOLUME setting to 17 to 21 grains and use pyrodex P. I have no idea the actual weight. Pyrodex is used on a volume basis, based on black powder. 17 grain setting was my standard for years, then lately wanted a bit more oomph so i went up to 21 grains. With black I got maybe 6 shots until the cylinder locked up from fouling and terrible accuracy. With pyrodex I get 30-36 shots before fouling locks it up. Remember, use a VOLUME setting for pyrodex, not a weight!! Set the measure for 17 grains volume and go from there.
Started using pyrodex in 1994 and so far no corrosion issues if cleaned like you shot black powder. It is imperative that before shooting you clean all oil out of the bore (I run an alcohol soaked mop down the bore). After shooting clean with a water based cleaner, oil it up, and you should be good to go.
It shoots accurately. Photobucket changed since I used it last....lets see if I can post this:

 

[dandak]

Oldguy03, somehow I missed your question to me. Sorry. Yes you are correct about the 3 different charges. I was simply testing how well the gun shot and how it felt with various amounts of powder. I do this several times and then take group averages. This target was used to test 18, 21, and 23 GN volume settings of Pyrodex. I'd have to dig up my notes to see what the actual averages were, but on this target 18 GN shot the best. I do know at the time I had 2 cartridge guns I shot a 17 GN volume of pyrodex in, so instead of 18 GN in this navy I just kept the measure on 17 and used it for all 3 guns. i should also add I use Ox-Yokes wonder wads that i dip in bore butter, but I have a hard time getting their 36 cal wads in place, so i use their 31 cal wads in this 36 cal navy. It works for me.

 

[dandak]

Yes 777 gets higher velocity over Pyrodex P with an equal VOLUME setting. I have chrono'ed many many charges of both and it has always been the case. I assume that this means higher pressure also (but am not sure).