[mrnominguy]

Hello gents.

I recently bought a DM9 that apparently hasn't seen play for the last two years. When I went to gas it up, there was a leak out the back adjustment area of the LPR. After I broke it down I found a small piece of aluminum shaving inside the LPR as well as a chip on where the set screw sits in and contacts the LPR body. I've cleaned and re-lubed the whole system, replaced the 007 o-ring, but the leak still happens. Can someone confirm that this chip would be the reason for the leak? And if so, suggest how I can get my hands on a new one?

*Picture incoming*



https://imgur.com/a/RrXXOPw

[mueller]

The chip on body as shown will not cause a leak, no big deal.

Look for....

- there's still some "007 debris" in the internal oring groove. Very common. May need to blow out with air and/or chase the groove out with a hooked pin

- HPR isn't set high enough

- the 010 and/or reg set on your brass adjuster

- LPR set screw is extra tight - set it in then back it out just a hair, it's only there to stop the LPR from flying out.

- the 012 outside orings on LPR. These rarely fail (except PM7 where you need to upsize them sometimes)

[mrnominguy]

Thanks for the suggestions. After diving back into it again i noticed some things that doesnt quite make sense, but i managed to get things working. I didn't catch that there was a nick on the forward 012 the first time, but the leak was still present after i replaced it.

At around this time i also broke down and fixed a leak in my Hyper 3 reg (and of course it was also the 007 deep inside the reg body that basically disintegrated)

After playing around with the LPR set screw like you mentioned i managed to get the gun to hold air! i thought that was the end of it, but after emptying the gun of residual air and re-assembling, i tried to gas it up again, but encountered the leak again somehow.

Turns out, for some dumb reason, if i tighten the back cap to the LPR to be even slightly snug, it will cause air to leak out. If i leave it loose (by loose i mean it might fall off cause its moveable by hand easily, otherwise it will leak) the gun functions fine.

Playing around with it some more i found that if the LPR setting was too backed out, or too tight, air would also leak. >

So basically i have a pretty princess ***** of a gun on my hands, but i finally got it to be playable lol. Is this possibly from an O-ring that isnt quite the right size or type? all the rings i replaced were nitrile, as i only have access to either those or HNBR at the moment.

[mueller]

Aye, the inner HPR and LPR orings should both be done as maintenance or you wind up chasing phantom leaks. Same principle for both - the groove needs to be perfectly clean from the old rotten ring and once it's done you're gold for 5+ yrs. I use buna not UR, works fine, doesn't disintegrate.

From there I've seen a few where the LPR body outer orings need an upsize to seal right. Common on PM7s. From what you describe I'd try that, it'll be a tight fit. What you describe sounds like this, the body is being 'tilted' by the cap (or a set grub screw can do same thing) and the outer body oring won't seal.

There's 4 ways the LPR can leak assuming the HPR is sound. In order of probability on servicing 100+ of these....
- inner oring - 100% failure over time, UR rings fail
- body oring - make sure no forces are "tilting" body, maybe upsize orings
- bad reg seat - rare but happens
- bad adjuster 010 oring - not sure I've seen one yet on 100+ markers

There's also factory mill grub screws rear-body and bottom of Matrixes that may need fresh loctite, depending on year. Often mistaken for LPR. This is where a stethoscope or a rubber hose from ear to gun helps to pinpoint leak source.

Bright side, once it's solved you're golden for years with only bolt maintenance.

[MstrKey]

The grub screw and back LPR cover are never meant to be tight. They're just there to prevent dirt from getting in and prevent the LPR body from sliding out of alignment with the internal plumbing of the gun......as well as to prevent the LPR from shooting out the back. Basically if it leaks when you do that......don't do that.