Where is the leak coming from?
Since you said it started after you turned up the velocity, I suspect it's coming out the back. Chances are you just need to clean out the back half of the valve. It gets rather grimey in there in a well used mag. You may need to replace the piston o-ring back there but usually a good cleaning does the trick.
If the leak is coming out the front you probibly need to replace the pt o-ring.
Either way as was said before the first thing you try should be a lot of oil and a bunch of dry firing.
Does it look like the zip-tie is holding the rail to the barrel? or is it holding on the expansion chamber? Is there a screw in front of the trigger going up into the rail?
__________________ FeedBack FS: Triggers/Sears FS: Pumps
Originally Posted by Marauder_Pilot
It will eventually get to the point where you're living in the back of a '78 Oldsmobile with a trunk full of the finest paintball gear known to man.