I just got mine going, after waiting for internal goodies to show up.
I used some Tetra-gas, BB-Bastard .28s, NPAS full open, and holy f--k!. Like was said elsewhere, "This thing IS a nail-driver. My buddy said, "See if it will break this bottle of beer"? First attempt...BLAM. Beer everywhere.
My question: About how many seconds should I fill the mags with Tetra gas? Same question for Propane, unless it's the same. I did 8-seconds, using what I do to me pistol as a referance, but it seemed like not enough. I plan on using Propane, but used Tetra because I have some lying around.