[Short Round]

This is my main problem now too. A bore up will help but it might not be a big improvement. Here's what i suggest

1: Ignore this step, see below post. *Thanks stryak

2. Hop up rubber, although you have it installed it may no be properly fitted into the unit. Now that is my current problem, you may not have that problem, I wouldn't know haha

3. O-Ring around the Piston head, this is a second problem I have now. If the O-ring is not perfectly fitted for your cylinder and piston head, the airseal will be very weak.

4. Spring, my third problem, check which kind of spring you have, mine is currently all weared out and bent out of place so its not performing to it's expected self.

5. Piston, your piston's teeth may be weared out.

Pretty much it could be ANYTHING lol, I may suggest taking it to a gun doc