I am lucky with my HF 6 gallon compressor. It ran the 2nd and third generation Snoeboes, and now the 495 dollar F10.Adjustment was right at the limit of my electrical ability these days, I faced the compressor while it was running, reached out with my right hand, while holding my manning glass, ssquinted my one good eye, grasped the pressure adjustment knob, turned it and it hissed slightly and slowly I adjusted it down to 125 PS.Like I said, a lucky break, got it the first time. Roachcreek
Another thing that I did notice when adjusting the regulator on the Shoebox was the fact that it does turn up kinda hard so evidently the spring in the regulator is a strong one. I only did a quarter turn at a time when adjusting mine. First mine would stop at about 3800psi and it took about three different adjustments before I got it to 4500psi.
I filled the Benjamin from 3000-4500 in 22 minutes.
The F10's are 1/3 HP John.