FWIW I had good results when I used the .444 with 8 grains of Bullseye using 300-gr. NEI #293 as a "blooper." These days I do 6 grs. of Bullseye in a rifle chambered for the .44 Magnum case, with same bullet. Almost silent in a 24 inch or longer barrel, brass easier to get, and ballistic uniformity much better not having the excess airspace. The .44 Magnum in a rifle has enough capacity for thumper loads too if you want them. For the bloopers use standard large rifle primers, no filler is necessary. Works best with soft alloys not harder than 8 BHN, bullets as-cast and unsized, lightly coated with Lee Liquid Alox.