When I use to shoot in Civil War "Skirmishes", from 1968 to 1976, a measured amount of loose 'Cream of Wheat' was put on top of the reduced Black Powder charge (of, approximately, 45 grains of FFFg) in Smith's, Maynard, Gallagher, and Burnside carbine cartridge cases.

The reproduction cartridge cases, for these carbines, held too much powder for accurate 50 to 100 yard target shooting. The 'Cream of Wheat' filled air-space and also prevented 'bullet lube' from contaminating the powder. A slight compression kept everything positioned in layers.

This worked well in this specialized application and these C.W. Percussion-Carbines were accurate and fast.

The .50 to .54 caliber Pure Lead carbine projectiles weighed around 350 grains and were lubricated with a Beeswax and tallow mixture. The cartridge cases were 'straight-walled', withstanding BP pressures in reduced-loads, a whole different cartridge situation.