I have my speed set at about 3.5- 4 at 27 volts for this gauge material.
I push the gun, using about 1/2" stickout.
Cleanliness is next to godliness (scrub scrub scrub).
If the back side of the work piece shows signs of blow through, go faster, or turn down the volts. (turning down the speed just gets you into glob transfer and makes a mess)
Good luck and practice on scrap first.