Seems like the battery powered vacuum cleaner mentioned way back would be the ticket, no fiddling with the bolt, getting something to fit in the chamber and the best of all, like mentioned, it will fit over a suppressor, any size barrel, and a little electrical tape to protect the finish on the barrel, I have seen ones the act as a vacuum and a pump and they definitely pull a lot of air.
Set it in the rack and slip the modified hose over the barrel and punch holes with a different rifle for a bit.
Might get some strange looks from the geezer on the other end of the line with your new fangled gadget