Back in the late 50's and on into the 70's we had DuPont then GOEX and sometimes Curtis&Harvey and sometimes.Kings even though the mill closed in 1953 there was still quite a bit around.I used 3fg in all calibers of rifled including a W.W.Greener 16 bore SxS rifle and it regulated at 50 yards with 90 grains and a patched ball.75 grains of DuPont and the old Lyman 451112 made the Whitworth happy and 55 grains worked in the Len Meadows flintlock with a .445 patched ball and groundhogs gave testimony to that load.My experience with Swiss is very limited but using 75 grains of it and the same bullet seemed to have a lot more punch and higher velocity but no real good way to know for sure.In 2008 I actually completed 3 rifles,a 58 caliber flintlock that I used 75 grains of GOEX 3fg and a .562 round ball with striped cotton patches.Bill Large would come back from the dead if he ever found out about that undersized ball but it worked.The next was a 40 caliber boys rifle with a .395 ball and the same patch material over 40 grains of GOEX 3fg and then,a 38 caliber bullet gun with a Hoyt barrel and a 330 grain lubricated bullet and 55 grains of GOEX 3fg and all came from the same can.That was my last tests with a muzzle loader and then started into another venue of black powder and shot at Ralph Marcum's Hooten Holler range in McKee Ky.for several years.
Bob Roller