I think that they meant to say that you could refill it from a SCBA tank (4500psi), not a SCUBA tank(3000psi). If you use a SCUBA tank, you won't any any full refills after the pressure drops below the 3000, or so, fill level of the gun. If you're willing to go with lower fill levels, it can work. I have a Maximus (2000 psi fill level), and calculated 80 some refills from a 3K psi SCUBA tank. I also have a SCUBA pony tank that's easy to carry around, that I can get about 7 refills from. If I were using a 3000 psi fill gun, I wouldn't be getting any full fills.