Brian,
In my 410 pistol,I use 444 Marlin cases with case polishing media as the shot and wads cut from stryofoam meat trays, for carpenter bees. These loads are great fun and don't harm the bottom side of metal roofs.You have to use a fast powder to get good combustion with the very light "shot". It won't be long until the "bee season" opens again.I don't see any reason not to use a nicely stocked bee gun.
Mike