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

Ok. So I have check all of the above issues and still nothing...
Springs seem to be in the correct position (I don't have a working one to compare it to)
The roller is working nicely.

One thing I did notice is that I can put a mag in the lower receiver, and fire it with only a quick pft. I expected it to vent the hole mag. I re-disassembled the trigger group and the spring that pushes the hammer forward appears to be ok and not bent or broken.

What about firing pin? Specifically the part that push the release valve? I know WE uses craptastic material which can wear off -this may result in non-fully depression of the release valve (firing pin lever). I've personally seen this happen with RA-Tech steel firing pin (they sell a replacement firing pin 'lever'

as you cock the hammer does the firing pin stay forward in the magwell and then snap back? or does it go backwards immediatley as you draw back the hammer? sounds like a broke delayer/locker to me

firing pin was replaced with a new one, still no change.

As I cock it there is a delay before the firing pin retracts. (the delayer is not broken I just replaced the broken one)

Sounds like the issue I had trying to fit my CNC'd lower to my trigger pack on an AR-15 type GBBR. The pin was too long as the lower was extremely tight, and it was getting caught above the valve pin instead of behind it, even retracted. Essentially I would get vents, or light strikes. I had to solve it by slowly filing down the firing pin until it wouldn't bind on the valve pin, but behind it as it should.

I had a similar problem with my WE G36K. I checked every where until my gun doc noticed my barrell was woobly a bit. I ve got to thighten it back, and it went back to normal.
I hope that could help. we never know

That sounds like a knocker pin or carrier indeed.
Also source and try new hammer springs. I had to swap mine after a year or so, I was getting light strikes.
As mentioned, check for a worn or cracked striker lock/disconnector. It's the silver part that always fall out when you remove the trigger pack from the receiver

I had repaired my friends l85 with a cycling issue, which is one reason I personally dislike the weapon. Anyho I had stripped the bolt carrier and assembly right down and used engine cleaner on the rods to clean any deposits. I also did the same to the bolt I applied it with a q tip. I had reapplied some clp to the bolt and rods oh and I also added some o rings where the bolt hits at the rear plate where the rods connect to act as a cushion instead of being metal on metal. I hope it makes sense and helps you out.