In regards to the protank, have you looked at all the O-rings to make sure they're seated properly? Also there maybe some fragments of metal from the milling process that are stuck in the groovesof that bottom cap. If you still have trouble I would definitely take it back and raise hell you definitely got a bad tank, it happens. Quality control. also you will notice over time that you will get gurgling and spitting overtime because the top and bottom o-rings get compressed and decompressed every time you fill; also they will break downand and have to be replaced. I would go to a local plumbing store and get a variety pack of o-ringsjust see what size you needand that solves the problem with gurgling when or if that problem does arise for you; it did for me obviously happen in my case ...sad to say I will never buy a pro tank again..I now own a G-50 5ml tank and I couldn't be happier. I have yet to have a problem with it. I get monster hits from it works flawlessly, blows away the pro tank.
