New scuba setup

I love my Disco, and I know that using my pump is supposed to be good exercise, but.... This heat and humidity in Mississippi is rough on this old man. So, I bought myself a Catalina S45 scuba tank and a scuba fill . As I figure it I should get 57 fills out of this setup. A 3000 psi 45 cu ft tank filling my Disco to 2000 psi from a low of about 1200 psi. That is 15 shots per fill.

I thought long and hard about getting a 4500 psi tank but for the price , the availability to refill it , I don't think it's worth it. I like my disco , as is. Besides, it cost me $175 for the tank and only about $30 for the fill, with a 34 inch whip. Considerably less than the other, which means more pellets. :) plus only 5 bucks to refill the tank, locally.
 
+1 to JSB (15.89 domes are my Disco's favorite, so far) and H&N FTT. If yours is new, which sounds like it is, shoot it a lot and give it some time. As it breaks in, the groups will tighten up. If they're still a bit loose after break in, consider a re crown. It's easy and can fix a "loose shooting" gun. Congrats on your filling solution! You will get many fills outta that tank. I've been wanting to pick up a pump to take with me when I go out in the field (to leave in the car, I mean, not pack out with me), just to top off if needs be without all the hassle of bringing my scuba tank. What kind of pump are you using?