MY GUN WON'T SHOOT ABOVE 200\220\240\260!!
Couple of things to check here. Is your vertical regulator lubricated and its seals in good condition? What are your pressures at? (They should be 230 on the vertical\inline\HP, and 80psi for the LPR) If none of that fixes it, remove your engine. Drag an oring pick through the groove in the rear of the interior of your Marq. Did it have debris\oring chunks in it? If so, replace the outer engine orings. Still doesn't fix it? Consider replacing your poppet, especially if it's an older marker...they get worn. Also, verify that the holes on your engine are correctly aligned..they should look like
THIS.