Interesting comments.
Previously, I've been taking my small "guppy" tank with me on my local trips to my permissions. Depending on which Marauder I take (almost stock .22 or my modified .25), the guppy was enough (about 7 refills). I did buy a big 88 cf tank from Airhog, but the small tank has so far been enough, unless I take more than 100 rounds with the .25.
I recently bought a W.A.R. Cobra which has a 450 cc, 4,500 psi tank. On the last three outings, I haven't needed to refill the Cobra as it will shoot about 60 rounds if you start at 4,500 psi. By the way, the regulator is set at 1,900 psi. The nice spinoff of this is, if I wanted to do a lot of testing, I could tether it up, and not worry about an external regulator. I suspect others are out there with the same capabilities.