We have been told the load consisted of 90 grains (3+ Drams) of 2Fg Black with 1 1/8oz of #6 shot. What we have not been told is "What Type" of shot. Even @ 1100 fps MV #6 lead or its equivelent should kill a duck cleanly to at least 40 yds. If the shot is the much less dense steel then #6 is about the equivelent of #8 lead, or less. I am thinking the kind of shot is the answer here.
While I too prefer real black to Pyrodex it should ignite quite well with a regular shotshell primer. At one point when I was having a hard time finding the real stuff but could get the Pyrodex at Wal-Mart I tried some of it. It did fine in my .45 cal round ball long rifle using ordinary percussion caps. I know a lot of deer hunters around these parts use it in their In-lines with total success & lite it with 209 primers.
I caught some 777 on a good sale & bought a couple pounds to try in a breech loading shotgun but haven't done so yet.
