I'm thinking about getting a Benjamin Maruader .177, but I don't know which size tank to get. I looked at a 80CF, aluminum tank . It would be 150.00. But how many shots could I get out of that size tank? Would I need to get valves or adapters to fill from it? I found a Marina that will fill to 3300 psi, that's only 26 miles from my home. I could use any advice you could give me.