we L85 not cycling
 

Hi,

So today after a few hours of play I get a mag vent. No bit deal it happens, so I fire in a new mag and I get one bb out then the I notice that the bolt is only going half way back. Since I have gotten home I did a full tear down looking for debris and found nothing. I am getting more movement in my bolt now but only 1 shot in 5-10 is getting a full cycle. Hop up rubber is good and I can see no tearing in it. I am using all stock parts at this point for the bolt system (carrier and nozzle).

The only thing I can think of is that:
1: for some reason the mags are not releasing enough gas (tried several mags)

2: something is stopping/slowing down my bolt from completing the cycle.

Any ideas?

Is your gaz can nearly empty?

It sounds like there isn't enough pressure in your mag.

I thought about that, I am filling off a brand new can now.

Your piston is dry.

Take the bolt out, and pull on the nozzle. You should be able to see the o-ring at the end of the piston. Apply silicon oil and move the o-ring to spread all around.

That means you don't use enough silicon oil in your adapter. Put a drop before each mag to catch-up, then once every 5 mags fill. The 1-10 instructions work for pistols... GBBRs use a LOT more gaz each fill.

Nope, I thought of that as well. I even took a spare air nozzle and lubed it up waited a few hours for it to absorb and swapped it and I still have the same issue.

did you check your hop-up rubber? If it's torn/worn/sticky it might cause issues.

Also check the holes in the back of the piston. I got weird issues when the two top holes got clogged by crap. Nozzle would move perfectly outside the gun, but when firing it would stick.

Checked the piston. As mentioned previously I swapped out with spares and same result. I have the aluminum ra-tech one in now and I am getting better results but still junk. I checked and cleaned the hop up rubber and it appeared to be ok but as it is the only thing I have not swapped out I'm running out of options. I have a friend with a spare stock hop up rubber that I can toss in to check.

Reading about your rifle's issues, and hearing all the things you've done to find the fault, I'd suggest you look further back for the cause of the problem - particularly in the trigger group.

My expertise is with WE's M4/16 chassis, so I have to make some guesses about how their L85s function, but my first guess would be that the hammer is getting hung-up, not fully retracting, and putting the brakes on the bolt's rearward movement. Take a look at that and see if there's a solution back there.

I thought about this but I have no experience with trigger groups nor have I pulled one apart. I'll set up a nice white work bench and get a camera going so I can pull it apart and re assemble. If the hammer is not fully retracting and hitting the bolt carrier on the way back where are some possible areas to start looking?

Ultimately, the sear. A less likely possibility would be misalignment of the selector switch's shaft as it passes through the trigger block.

Have you removed the lower and, putting the upper on it'S back, tried to cycle the bolt back slowly?

Even remove the springs, just to see if anything catches anywhere.

Swapped out the hop up and no change...

I can pull the lower right out and put the pin back through the upper receiver and it will hold the rods in correct alignment. Everything slides nicely with no binding what so ever.


I'll tear down the trigger box tomorrow. With everything else checking out it is the only thing left that can go wrong.

In the lower/trigger box, check for a cross-pin that is not seated properly.

Also check for a bent/binding spring. It can be as simple as the hammer spring slipping between the hammer and trigger box jamming.
Check the pin that holds the roller in place on the hammer. It is a common issue on the M4/SCAR/G36 platform. If not perfectly in, put a drop of superglue in the recessed side and put back properly. Wipe the excess right away so it does not creep in the roller and bind everything.

is there a crack in your nozzle,
is there a crack in the bolt carrier,
is the valves inside sitting properly?

no, and I have tried multiple nozzles

no. I am using a steel RA-tech one as well as the stock

Yes