577 snider with .535 ball in 1.8" 24 guage plastic shotshell powder suggestions?

[justashooter]

so i pulled down some more 11/16 oz 24 guage shotshells and cut the cases back to 1.8", which fits well in my egyptian sniders, and weighed the powder charge, which sales at 14.6 grains and looks like Red Dot or unique. the plan is to load the .535 round ball (230 grains) or a .533 minnie (410 grains) in teh power piston shotcup over about 12 grains of unique, but i am wondering if there is a shotgun powder comparable that more uniformly performs regardless of projectile launch resistance.

there is no room for black, which burns uniformly whether contained or exposed. i am wondering which powder in the shot-shell class is most like black in that sense. once i have confirmed firing, i will run this stuff over chrono, looking for 1200 fps, but am wondering if anyone has experience with anything like this for reference.

[Grapeshot]

Try using a .577 mine ball instead of a round ball. If it does not fir the cut back hull, you might want to try 24 gauge brass hulls. I'd suggest you stay with black powder in those old rifles.

[toot]

i use .577 MINNIES in my plastic 24 gauge CHEDDITE shells with out any problem.I put dried lint on top of the 2ffg. black powder and insert the MINNIE and VIOLA!!