The size of the tube needs to be bigger to get the kind of shot count and consistency a bulk gun is worth altering. Generally if you have a tube equal in volume to a couple of CO2 cartridges or set it up with a Hnagy tank arrangement it would be worth doing. The Benjy has a tube fit for a 8.5 gram cartridge so it isn't going to get a decent number of shots per fill or reasonable consistency if you just fit a Bulk adapter to the tube end.
It is one of those possible things that is a waste of effort at the end of the day.
"NO GUNS WOULD BE A RIOT"
Later
Tim
Mac1 Airgun