Speaking of the 4500 storage cylinders, I recently aquired 3 of them very cheap.. 2 from a paintball shop one from an individual. 2 had air in them one was empty and just came back from a fresh hydro. the two with pressure had a smell to the air when released so I drained/filled/drained/filled until one was clean smelling the other still stunk. I puleld the valve and sure enough it had about 1/4 cup water in it and some corrosion in the bottom. So tumbling with some simple green and maybe some nuts/bolts for abrasion should be ok? the one with a fresh hydro.. should I pop the valve out of that one too or do they pretty much do a visual on those when hydro'd?? Thanks for all the advice.