Do you have pics of the dump valve hole? I'm curious about the size of it compared to the Panther Tank.
The 'Range Master' also had the same 'auto' fire mechanism (looks to be the same tank actually). It was due to a weak check valve and not actually a true mechanism by design.
If it is the same design as the Range Master, constant tripping of this 'mechanism' will inevitably burst the check valve. When that happens, the tank will not be able to hold pressure. At least not without some modification/fixes.
Unfortunately i have no pics of the Dump valve hole, i made the blaster into a sledgfire shell shotgun before even thinking of taking a picture .
I don't think its the same tank as the range master, or i certainly don't remember them looking the same, I'm pretty sure its bigger.(took apart a range master LONG ago)