Tokyo Marui M870 shotgun Gas Leaks

[p.phresh]

I just starting getting a leak from the body, looks like the expansion chamber is leaking from what I've read in other places.

my shotgun is basically stock except with extended wiitech inner barrels.

haven't tried these yet, but I've found these solutions so far:
1) increasing the spring tension on the hammer spring
2) drop some silicon oil directly into the expansion chamber via stock
3) replace orings in the expansion chamber

has anyone had this gas leak and repaired it successfully?

[RainyEyes]

http://airsoftcanada.com/showthread.php?t=181667

You said Tokyo Mario and shotgun... So I'm assuming it's the m870.

Take a look at post#7 for a possible fix. It's a long vid but Ive successfully done this fix on 4 shotties. I'm still working on a guide/fix for the TM non-propane rated gas tanks...

[p.phresh]

thanks rainy. I think this is the fix I'm looking for.

the video and audio was out of sync while watching from my phone but I think I got the idea. get the quad ring (size 104) and shape it to be conical to match the chamber wall.

bath orings.
Teflon tape and Grease the remaining orings.
reassemble and hope for the best.

do you happen to have any extra quad rings?

[RainyEyes]

I literally used the last quad ring last Saturday, sorry. You should be able to buy them from any hydraulics shop. 70 durometer should suffice and the good thing is they're cheap. It's the labour that's tedious and painful. Good luck.

[Styrak]

Anyone know if buying the high output valve would fix the leaking issues? One of these:

http://shop.ehobbyasia.com/sat-high-...l#.WX97FFGQyUk

http://shop.ehobbyasia.com/pro-arms-...l#.WX97F1GQyUk

[RainyEyes]

Originally Posted by Styrak

Anyone know if buying the high output valve would fix the leaking issues? One of these:

http://shop.ehobbyasia.com/sat-high-...l#.WX97FFGQyUk

http://shop.ehobbyasia.com/pro-arms-...l#.WX97F1GQyUk

IIRC I remember reading about those and they still leaked. The only thing they fixed is the rear seal where the sear releases the firing pin since it can leak from there.

The spring is definitely stronger in SAT valves but the inherent problem is that the o-ring doesn't sit flush with the cylinder once they start to shrink. The marui and sat o-rings are all 70 or 90 durometer but because of the way the valve is designed it doesn't come into silicone oil from the gas and is prone to shrinkage.

Here is the JAG Shotgun (marui clone) design.









They actually made it into 2 pieces so that the o-ring sits on the firing pin like a pistol piston. It gets secured by a screw but the cap that the o-ring sits on actually allows extra room for the gas to fill the cylinder and keep the o-ring lubricated. It is the same 70 durometer o-ring used in the marui original but the way they've engineered it to work with green gas is good enough to prevent leaking. The JAG valve also had a MUCH stronger spring that further helps prevent leaking.

@stryak unless JAG releases their parts on the market I'm afraid the $2 hydraulic seal diy fix is the next best way to fix the problem. I've heard of people replacing the valve o-ring and after 500 shots it starts leaking again. I haven't had the same problem with the quad ring fix but I haven't reached that many shots yet.

Btw SAT is junk imo. Every review and every contact I have had with their product had failed.

SAT loading arms split in two:

[p.phresh]

Styrak, I've also read from one source that the high pressure output valves leak.

Rainy, you've done a comparison between the TM M870 vs the JAG arms scattergun? what have you found so far? are parts interchangeable?

is the expansion chamber a straight drop in fit between the two?