Avanti Valiant Air Tank

Is it just leaking like its an o-ring? I just purchased a Valiant and a S200, both are in shipment. From what I have read the ends can be a little difficult to remove and need a special tool.

Not in stock, but they say they are getting them late this month. I'd call them and ask. Air Venturi is the US distributor of Air Arms, which is the closest thing we have to parts. They responded to me quickly with my last CZ200 parts question.

 
Since you're new (welcome by the way) in the interest of keeping confusion to a minimum, when talking about a rifle's air reservoir, it's referred to as an air tube or bottle. TANK is used in referring to a SCUBA or SCBA used for filling said gun reservoir. I'm assuming you meant the Avanti air tube & not a refill TANK.
If you could describe what's happening with it, it might be an easy fix. Provide pictures too, if needed.