I figured it is possible just not too common..like you said it would need to be threaded which my barrel currently does not have. Plus with the powder would make it challenging. Thought it would be a good idea in case a guy and his partner are hunting together you would both at least get a shot if multiple elk/deer together
I've run a bunch 45cal suppressed. So no sabot to deal with. I ended up needing to remove every shot (even though I had a funnel to load through). At least back in Iowa with high humidity, if I didn't remove every time bore would condensate and soak my powder. That was all smokeless, so no need to worry about fouling. I would think it would be a mess with BH209. Easier to just wear ear plugs IMO.