It got a good writeup (will work in regular percussion and even flinters with real black 4F in the pan, which other subs I have tried will not) in Handloader. It is also hotter than 2F and much cleaner. As grains are quite large the usual volume based BP measure is not too accurate. With my volume brass cutoff measure set at 65, weighed charges varied from 52-57 gr. Alliant says it should be compressed, so I settled on 54 gr in the 45-70 (1885 Browning High Wall) each weighed on my Redding scale. A Lee plain base mold bought at a yard sale for 5 bucks, drops a 415 gr with wheel weights that shoots very well in my 1886 lever gun. As cast .4575 so all the .458 SAECO does is put SPG in the grooves.
Rifle has a 3-9 Zeiss on it and shoots three 300 gr Hornady or 400 gr Speer jacketed with serious loads of 3031 into 1 moa or less.
So I loaded up 20: 18 cast w/Alliant and two 300 Hornady w/3031.
Shot 9 cast at 50, group was 1.5" wide, 2" high. Bore looked a bit dirty but nothing like Pyrodex or real BP. Fired one jacketed smokeless through and the bore looked brand new !
Moved to 100, 9 more, group was 6" wide and 3" high .... huh ? vertical spread turned to sideways ! Again a jacketed smokeless made the bore spotless.
Guess I'll have to slug the bore and get a proper NEI mold for it.
Also anxious to try this powder in my .452 Alexander Henry Replica that is good for about 4 shots w/2F before needing a swabbing out.
And my c.1809 61 caliber Baker flinter that was designed for the patched ball to be started with a hammer) each soldier was issued a wood hammer, an example may be seen at The Rifle Brigade Memorial in London:
It is a very effective weapon !