Burrard listed both standard & Low Velocity loads for the 4 bore in 4" & 4¼" cases. Standard was 9 dram x 3¼ oz for the 4" case & 9¼ dram x 3½ oz for the 4¼" case. The LV load was 8dram x 4oz & 8¼dram x 4oz respectfully for the short or long case.
1904 rules of proof show the 9dram x 3¼ozload as the "Service Charge" for all bbls proved from 6 (.919") through 5/2 (1.026"). Note that true 4 ga dimensions (1.052") are seldom found in shotguns as most were built for paper cases with a bore dia of about .935" & proved as a 6ga. Chamber dimensions had originally been set I believe for round ball guns using Thin Brass cases. All above loads are Black Powder loads of course, but smokeless was similar.
