I shoot a lot of smokeless in these old BP military cartridges as most of my molds produce bullets that don't hold enough grease for effective black powder shooting. I had watched a video on FortuneCookie45lc channel on using Hodgon 777 as an alternative powder during the current reloading component shortage. I thought I would share my results and I do think this powder will work for me in a variety of obsolete cartridges and a few current ones for that matter. I have tried Pyrodex in the past but find it to be very corrosive and a pain in the neck to deal with, I much prefer real black powder when I have a good mold to work with it.
I bought a couple pounds of H777 FFG to experiment with. I loaded some up in both .41 Swiss and .43 Mauser, as soon as I empty some of my 50-95 brass I am going to try it in the 76 Winchester. H777 is pretty dense so you get quite a few more loads per pound. In the .43 I used 80 grains by volume which came out to 56 grains by weight with a Accurate 45-370Y heeled bullet, in the .41 it was 50 grains by volume and 36.5 for a weighed charge with a Accurate 43-335B bullet (100% load density is called for). I used CCI large pistol magnum primers (as I have a surplus of them) both had a milk carton wad between the bullet and powder.
The .43 was fired through a 1871 Mauser (single shot), and the .41 was through a 1869/71 Vetterli carbine (cut down rifle). Distance was 50 yards, the .41 plate was 9 shots the first 2 of which were just under the plate with a 6 o'clock hold. Both shot pretty well and I will continue to work with them. By recoil the H777 rounds felt "hotter" than any of my smokeless rounds and per the Hogdon site H777 has about 15% more energy than BP. The H777 does leave fouling in the bore but the bullet lube seemed sufficient to deal with it. Clean up was pretty easy, hot water is recommended I used 10:1 Ballistol:water.
.41 Swiss
.43 Mauser
Tom