Edit: Ahh. See the post below mine.
I never heard of top gas before so I googled it, most sites seem to reference it as HFC 134a. If this is indeed the case, then you CANNOT use it in a gun meant to run on green gas, which is propane. Well, you could, but the gun would not function correctly. So to be clear top gas = HFC 134a, green gas = propane. You can use propane in an HFC powered gun, but it will wear the parts faster. You can't use HFC in a propane gun because the bolt will not cycle fully.
Last edited by Rommen; June 28th, 2012 at 18:03..