In my case this is how I'm going at it. My 8cuin gets approx 80 shots on normal paint with a smooth bore barrel. When lapco finishes the fsr I requested ill be using that and I'm sure it eats my air than smooth bore. So you figure somewhere less than 80 shots with first strikes through a rifled barrel. So whenever I go to fill up in air ill refill mags. So I only need enough mags for the tank capacity. I'm going to start with 5ripper total mags including tthe one in the marker. That's 45 rounds. I'll buy extras as needed once I know my total shots per tank with this.