I looked through UMC catalogues from 1887 to 1909 and found they offered their "Best" Quality brass NPE in a 4-inch 4-gauge --
and a "First Quality" (brown) paper NPE in 4-inch 4-gauge for black powder only. 1887 --
1901 --
The only loaded 4-gauge shell I found offered was the Yacht Gun shell loaded with 18 drams of black powder.