Still working on it but delayed a few years. I have a single bbl .410 3 " chamber, funny a .357 mag round uses with some powders any way, the same charge as the 3 " .410 with it's much heavier shot charge ..... I have a bit of .41 mag pistol barrel threaded to the end of the .410 about 4 inches. Have had some encouraging results using .357 powder charge and 225 gn lead .41 mag slugs - pressure still way under problem levels. With time this will translate to the .410 equivalent of the paradox, heavy for bore projectile at still moderate velocity, my chrono was on loan at the time so no velocity data yet but expecting to get at least 1500 with the 225 gn bullet through the rifled section of the choke with good grouping. Will repost when I get some concrete results and pics.