Is there such a thing as a little handheld CO2 gun that I could use to purge my bottles prior to bottling? One thing I'm toying with is buying one of those whipped cream dispensers, they take NO2 canisters but I'm sure that's ok, better than air and it might be able to take a CO2 bottle. I'm just wondering if there is anything else I can use, there are little bike pumps but I assume they have a valve connection so could not be used on an empty bottle. The other thing that's more expensive is a soda water machine, you get them as handheld machines that I assume can be used empty to just dispense CO2 but they look pretty much the same as the whipped cream machines which are cheaper!