That's how I understood the origin of the 3 Dram eq. traditional nomenclature, was that it would give 1 1/8 oz. 1200 fps. MV.

Retained velocity is also dependent on shot size.

At least Western Cartridge had the sense to not use English 6's in heavier loads. The whole point of the heavier load is to use larger shot, that's where the longer effective range comes from.

"The price of good shotgunnery is constant practice" - Fred Kimble