I just thought that as I'm not an expert, I'll show you what I use for my DM7 when I have problems.
Granted these tips are for the Pm series of guns. I imagine someone is going to be a jerk here and say I don't know blah blah blah, but the operation is similar and this might give you some more ideas.
So please don't bash me for just trying to help.
"--I have erratic velocity or shoot down problems--
Piston (10) or shim stack (9) may be binding due to excessive dirt or lack of lubricant.
Seat (5) may be dirty or damaged. Clean and grease regulator. Inspect and replace damaged parts as needed.
Make sure shim stack (9) is stacked properly."
"--I am getting inconsistent velocity over the chrono--
In-line regulator not giving consistent pressure: refer to the Hyper2 section below, or if using an after-market regulator, refer to its manufacturer.
Low battery: change the battery.
Bad seals in the bolt: take out the bolt, clean it, lube it with Dye Slick Lube. Replace any orings that seem damaged, swollen or in otherwise bad shape. Most likely the o-ring at fault is the #017 UR70 (5) front wall o-ring. Also check that the #014 BN70 (1) o-ring on the bolt tip is in place.
LPR pressure set incorrectly or LPR pressure fluctuating: if pressure is too low, the bolt will not cycle correctly. Try turning the LPR pressure a bit higher. If the pressure seems inconsistent, you can have an authorized Matrix center check the LPR pressure. List of tech centers can be found at www.protopaintball.com
Dwell set too low: if you set the dwell too low, the dump chamber will not empty completely and will cause erratic velocities. Refer to board settings on page 6 for information on setting the dwell."