because when I bought mine, Jim at Precision adjusted it up for me in his shop. It was at 940 fps with JSB Kings, I wanted it at 930, so he turned it down. 940 is 49.75 pfe. I had barracudas at about 53 pfe, but they did not group well. MIne is a MKI, but I added a reg and new valve. I shoot mine at 920 or 47.62 fpe, and at fifty yards it is very accurate. What I noticed is that at 930 fps, there is a muzzle flip and louder sound out of the gun. I think the pickle at the end is designed to handle only so much air and only so fast. When You keep it closer to 45 pfe, all the harmonics stay happy. When doing chrony work, my air was low and the gun was at 900, 890 fps and the shot sound was just a puff. The pellets were grouping very well. I still need to have a windless day to test 920 against 890, but have not had that time.
Winds light and variable!