The reason I could guess your gun is "been there done that". On mine I start at 2900 psi and get 45 shots in the 20 fps window. You won't get a full match out of it so don't try by overfilling the gun. You can't go by my numbers so you still need to get a full string measured so you will know where you are at.
BTW, my Huntsman Regal is capable of competing with anything accuracy wise in Hunter class FT. You just have to refill mid-match.