Number of fills to be had from a scba carbon fiber tank

I I would like to avoid needing a compressor to service my first pcp air rifle. I need to know how many fills I would get from a 100 cu. ft. carbon fiber tank when refilling a 300 bar bottle gun that would be filled to just 250 bar and run down to 150 bar before refilling the rifle's tank. I live only 15 minutes from a dive shop and refills, for any size tank, would be $15.00. Then, depending on the weight of the pellet/slug and the power setting, I could count how many shots I would approximately get from each refill. This is why I am considering rifles that are efficient in their use of air (and a large capacity bottle for more shootin' and less fillin'), such as an AGT Uragan or a Daystate Red Wolf HP, either in .22 caliber. The large shot counts are less important for hunting purposes, but I would enjoy, I am sure, introducing not just myself but others to the challenge of plinking and target shooting with these marvels of technology. In my powder-burning days (high power rifle with an M1; bench rest, and woodchuck hunting with a small bore 22-250) I received great satisfaction by introducing some shooting friends to hand loading. Yes, I would be opting for paying up front for a more enjoyable experience thereafter in this new shooting adventure! Next: to find someone who has enough property in my area (Quakertown, PA) that would allow me to set up a portable bench (and backstop if necessary) and allow them to share the modern wonder that is shooting a top-level PCP air rifle. 

Thank you very much for your replies. I am an old man and relish the notion of returning to shooting in this new venue. Enjoy your own shooting and share with others. You will find yourself blessed more than they will.
 
I need to know how many fills I would get from a 100 cu. ft. carbon fiber tank when refilling a 300 bar bottle gun that would be filled to just 250 bar and run down to 150 bar before refilling the rifle's tank.

Without the size of the bottle/tube on the rifle, the calculation is not possible. However, If I assume 300cc for the bottle on the rifle I get ~16 fills.