G36 firing oddly in semi (1BB,2BBs,1BB,2BBs,1BB etc.)
 

The problem seems to sort itself out with a higher current battery, but I'm using a 1700mah battery now and the G36 shoots 1 BB in semi and then it will fire 2 in the next shot, then 1 in the next. I'm a somewhat experienced person with AEG internals so I presume it is a relatively simple matter of gear timing, and setting the anti-reversal latch to lock the bevel gear at the right time. But if it is a gear timing issue there should be 2 BBs every shot. That is the part I don't understand. If anyone can offer some insight on the matter I would greatly appreciate it.

Theres no such thing as gear timing.
A sector clip tends to fix all feeding issues in V3s. Otherwise its a good bet that its your tappet plate, how many rounds have you put through your G36?

Any chance your hop up unit has undergone some work recently? If the little clip that holds the barrel to the hop up unit is evena bit cracked, it'll allow the inner barrel to move a bit forward, causing double feeding. Found that in my MP5, fixed it all up and instantly got semi shots every time.

Is your hop-up turned all the way off? If not, turn it all the way off, put a shot of silicone in there and see if the double feeding continues.

If it's OK, the run a couple BBs through it and reset the hop-up. AEG hop-ups need a bit of silicone oil on the rubber to facilitate smooth feeding, as described in the owners manual for the gun.

I know it's retarded, but I've gotten into arguments with a guy over that, he says it's all because the owner insisted on putting a tightbore in, cuz "tightbores jam all the time", and no matter how much experience, explanation and pressure of proper maintainance, the owner always asks me to install his stock barrel back in becuase his M16 keeps plugging up............ in the hop up.

What about mag feeding issue? Is that a remotely possible cause? Does your problem still occurring using a different mag?

I've found that guys will use a gun for years, never perform any maintenance or lubrication, and an issue of double/misfeeding has come down to no lube in the hop-up. It's a quick and easy test to see if the problem lies elsewhere.

I've dealt with that numerous times, so much that I actually take oil to most games with me to fix guns. Is retarded though to hear plugging being the cause of a tightbore. Honestly, just to dispel the myth, I did a search on all of ASC, tightbore+jamming, I came across about 6 threads, all of which were posted the myth "what tightbore should I get to keep it from jamming?"

Oh it's not the magazine lol
My UMP has the strongest mag springs I've ever seen in airsoft and they do the same type of double feed 1-2-1-2.
I'm fully confident a sector clip would fix it, but I always keep it in full auto and tap off 2 round bursts.

Coincidentally I just got a KA sector clip. I can't wait to put it in. I heard the ver2 KA sector clip is the one to get.

It's definately not the hop-up because I worked on it yesterday. I bought new hopup rubber from the toronto airsoft convention. It's not magazine related. It's all well lubricated. It works perfectly fine in fully automatic and that's what I usually play in.
The only possible thing that I can think of to explain the weird feeding issue is the current cut-off lever, and I have no idea how it works.
In order for this situation to be true, I figure the nozzle would have to move in 3 directions per shot in semi. On the shot that fired one BB, the nozzle would start fully to the rear and finish fully forward ( BB is fired after nozzle moves forward for 1st time and a BB is chambered after it moves forward the 2nd time). The shot that fired 2 BBs would start with the nozzle fully forward, end with it fully to the rear, and 2 BBs would be fired after the nozzle completed its forward motion and chambered another BB.
and all that craziness comes down to the bevel gear turning too much, and being locked by the anti reversal latch when it shouldn't be. I'm thinking too much but I'm just trying to understand why it happens.

Thanks for the sector clip idea guys. I'll have to get me one of those me thinks.

Is this gun stock, or has there been replacement of internals, namely the sector gear, tappet plate or nozzle?

Just your super basic upgrade. metal bushings and a higher power spring, probably around 150%.

I haven't seen this problem in a Marui G36, but I did see it in a G&G UMG (basically the same gearbox arrangement).

The G&G was a brand new gun. When they first came out, G&G acknowledged a defective tappet and offered replacements. The gun I saw failed to feed, so initially I thought that the tappet was broken, as this was a known issue. To my surprise when I opened the mechbox, the tappet was intact. The problem was actually shimming. The sector gear was shimmed so that it basically bypassed the tappet. When the gun was assembled, the sector nub barely grabbed the tappet, like in the thousandths of an inch. After about 40 rounds, it wore the little bit of the tappet away that it did grab, and ended up bypassing it.

I re-shimmed the sector gear so that it engaged the tappet correctly, and altered the other gears to match the sector. To my knowledge, the gun has been running ever since.

Continuous stop/start cylces in semi may allow some lateral play in the sector gear, so that may be why it happens alot in semi vs. full. Usually, once a gear starts spinining it likes to stay in that position, sort of like a gyroscope. This may be why your feeding problems aren't as noticable in full auto.

It's worth a look.

I just did some tests and I found that every other shot, the nozzle was about 2 milimeters forward then it would be on the shot before. When it was more forward it restricted any BBs from getting into the chamber, whereas when it was more to the back, there was room for a BB to get in.
just disregard my theory a few posts up lol

I find that in semi the nozzle ends up at all kinds of various places, halfway, full back, almost full forward (2mm from breech). Really, there's nothing you can do about that, they all do that in semi. Only way I can get the nozzle to sit full forward is to fire in full auto until it rests full forward.

I stil say the hop up wasn't installed preperly, that's largely what causes double feeding, the nub is too far forward, enough that a second BB can get in the nozzle's path.

Just a point to add here;
I have noticed that when changing hop up buckings (as I do to about 15 AEGs every season...team gun maintenence...every spring), I have found that when working with full metal hop up units and/or tight bore barrels, that I have to be particularly careful when sliding the barrel back into the hop up unit not to have the hop up bucking pull forward, as this results in the feed end of the bucking stretching into an oval shape. This slight "out of round" causes the nozzel to catch the excess hop up material and jamb when feeding a BB.
This is a real pain when trying to initially instal new full metal hop up units, and I have found it to be a very common problem.

SHA DO

well I shot a low cap off and did not get a single double feed in semi. The problem might come up again with more use but for now its off my mind. I think it all came down to the hop sleeve. I noticed that it was pulled off the barrel just a little bit and probably had the oval thing goin on, and the feeding end protruded too far back. After a quick adjustment to the sleeve it all seemed to work.
It is just the consistency of the 1-2-1-2-1-2 shot pattern that boggles my mind. It wasn't just a random double feed here and there, it was every other shot without fail.
A simple solution to a complicated problem..for now...

i had this issue with my G36 when i first got it, the problem is fairly easy to fix.
its not the tappet plate or the nozzle. its in the hopup assembly.
if you look at the hopup assembly, on the underside of the area just befor the entrance to the hopup openning, there is a small spring mounted ramp.
that ramp is there to stop BB from being pushed into the hopup more than one at a time, but if the mag spring is a little too strong it will push a second BB up and the first BB forward.
to fix this all you need to do is take apart that ramp assembly and replace the orriginal spring with a stiffer one. thats it, and after that it should feed fine.

thanks Dynamo. I was wandering what the ramp was for.

I had the same patern double feeding problem with a felow's AUG. Ended that the hop chamber was damaged.

Changed for a PDC metal one, no problem since then.