Back in the earlier years of The Double Gun Journal, there was an article on the restoration of a Greener Empire grade gun, with a photo of the mid 90s year old guy who had accidentally blown the gun up, and lost a few digits out of the deal.
I seem to remember they loaded black and smokeless hulls in a variety of lengths, and I think the article makes mention of the fact they considered store bought loads, inferior to their home rolled loads. They were rural Canadians, if I remember correctly.
Ill have to see if I can find it. Pretty sure the gun was sleeved. I dont remember what the chamber length on the gun was, but, it seems to me they did not seem overly concerned about what they fed it.
Best,
Ted