I'm kicking around a couple ideas for a short range .410 slug load.
I've got Magtech brass, Circle Fly overpowder and cushion wads, and a 38-55 (0.379" dia) bullet that casts at 325 grains which equates to the old 3/4 oz shot load.
What I'm considering is paper patching the 38-55 soft lead bullet up to my .410 full choke's "as slugged" diameter, and using Fg black powder duplexed. After having a good chat with the boys in Lewiston, also known as CCI, their info relates that smokeless loads in the Magtech brass causes swelling of the base of the case, which then requires full length sizing with a special die to get the base dia of the brass reduced back down to specs. I'm hoping to avoid that by duplexing, which should also keep the fouling down.
I'm going to chronograph and adjust to establish a velocity of ~1100 fps, which is within specs for the old 3/4 oz 410 loads.
I guess that, long story short, I'm going to try and (re)create a 40 cal black powder cartridge that fits my 410 for use in fairly heavy brush where shooting distances are short.
Anyone have any experience trying this, can see any pitfalls, or have any recommendations?