try resetting your low pressure reg to factory starting point.
go to http://forums.matrixowner.com for info on how to do this. noids will only leak if over-pressurized by the lpr. a different bolt will not correct or cause this. dont give up. if necessary, my local store has a matrix tech, or i can look at it. i love my dm4, and it is the most dependable gun i have ever had. i gas it and go. thats all.
are you sure it is from the noid? noid leaks are in the grip frame. leaking fron the barrel, and out the back of the gun are fron the bolt, not noid. you greasing correctly? you barely use any grease at all on the bolt. if you grease the o-rings it is pretty much all you need.
please send me an IM if you need more help, and ill see what i can do.