G&G AK 1st shot fine following shot barely make it out the barrel

[Ares]

I own a G&G AK, I have had to replace the piston (old one got its teeth shredded). This is my loaner gun so I put in a SHS full steel 14 teeth piston and a 100 spring in and have just replaced the rubber hop up boot.
When you fire the gun the 1st shot goes off just fine but all following shots barely make it out the barrel.
Any ideas?

[Styrak]

Did you make sure the nozzle is on the tappet plate, and the tappet plate spring is in place?

Could also be a problem with your hopup rubber.

[Jawz]

Penn,

It sounds like an air pressure/airseal issue. However, yours is quite severe. Therefore, I tend to agree with Styrak and believe that you may have forgotten to re-attach the tappet plate spring. In this case, the ASN (airseal nozzle) wouldn't be able to establish a good seal with the bucking and you get FPS readings of <100. Don't ask me how I know that...

BTW, this little faux-pas happens more often than you think...

Jawz

[Ares]

Thanks you two, I have since took it apart again but before I could see if what you both feel is the problem the spring ended up lauching and knocking a few peices loose so I'm not sure. I have taken great care and re-assembling it <crosses fingers> and just need to wait to get out to see if it works now.

Thanks again.

[Ares]

Ok had the gun out today with a fully charged battery and the same problem is arrising, but after further inspection when looking into the hop up unit from the mag well you see the air seal nozzle move forward on the 1st shot but it's not fully retracking to allow the next ball to feed or the gun to fire properly.

I have made sure the nozzle is attached to the tampet plate and all springs are attached, any thoughts???

[Jawz]

Penn,

Please test if your gun has indeed feeding issues. Sometimes the movement of the ASN (air seal nozzle) is too fast for the human eyes to reliably determine whether the former has been retracted properly:

- Take your mag and insert it.
- Turn your AK upside down, take out your mag, and put it aside. This way, the feeding tube of your gun is filled with BBs.
- Gently put your finger on the feeding tube to close the former, point your gun to a safe direction, and fire some rounds in semi-auto.
- If you can empty all the BBs inside the feeding tube, your ASN is retracting properly.

BTW, have you replaced the ASN or is it stock?

Jawz

[S_Okita]

I noticed this on his gun (know him in the real life). the air nozzle actually stops either closed or half way retracted in the hop up tube that enguages the mag. it sits there like a gate blocking bbs from entering the chamber sometimes and other time it decides it wants to go all the way back.


edit: he has the stock air nozzle seal on his gun as far as either of us can tell. its a black plastic one.

[Ares]

yah what he said =)

[Jawz]

S_Okita and Penn,

I understand what both of you are saying, but just because the ASN *stops* half-way when you look through the feeding tube, it doesn't mean that the ASN blocks the BBs! ASNs usually stop like that because the remaining energy in the motor causes the motor (ie. the pinion gear) to slightly overspin and therefore pull on the tappet plate, which in return pulls the ASN. Do I make sense? You already confirmed that the gun does shoot (which negates the option that the ASN is blocking the BBs) .

On this note, I guess you guys could try a different mag . I would actually like to find out if this is a feeding issue, and if so, where the problem is: mag-related or hop up unit-related.

BTW, could you be more specific when you say "you fire the gun the 1st shot goes off just fine [...]" are you referring to the 1st shot after the gearbox has been re-installed into the receiver or every time after the mag has been inserted? And what's the behavior in semi-auto versus full-auto?

Jawz

[MaciekA]

You should post a well-lit, high-res picture of the inside your gearbox. Maybe it's something simple that people here can spot, like a missing sector chip or malformed tappet plate (or something wrong with the tappet plate spring... etc)

[Ares]

I put a fresh battery in and insert a fresh mag and the 1st shot has good velocity and pressure and any following shot on semi or full auto just barely makes it out the barrel and falls to teh ground. On semi there is a BB each and every shot but on full you get the odd dry fire.

This is all using the factory high cap mag which fired fine before I replaced the piston.

Working on pics.

[DoctorBadVibez]

I'm not an official gun doc on ASC so please consider that before following these steps. While I can only offer advice, contacting your local ASC Gun Doc maybe your only course of action if any of this seems complicated or headache forming (go aleve). I am merely suggesting different scenarios other than what others have posted, to further compliment the input you're getting.
This is all based on personal experiences with fixing the guns that I own, those that other people give me the gracious oppurtunity to fix and my constant fixation with finding the perfect fps/range ratio.

Things that can go wrong:
When you replaced the piston, did you check to see if the piston head diameter matches the one you replaced? (Out of three guns with low fps that I fixed, one had this cheap piston and no way it could make consistent compression)
Ok, pistons good, what kind of packaging did the o-ring come in? If its a non airtight, rather dry instead, it may just be the o-ring itself, its shriveled up, put it in some light 100% ge silicone oil for a bit you might be able to gain back your fps. There should never be any non lubricated rubber other than the hop up rubber. (That saved a couple of good builds here and there packaging for o-rings need to get to industry standards).
Failing the abovementioned, did you change your cylinder? OR damage it (squishing it) My personal AEG did terrible with a bore up cylinder on a SR16 standard length 6.04 barrel, it did a LOT better with the standard marui cylinder swapped in. A squished cylinder, toss it.
There's a thread somewhere on cylinder size to barrel volume somewhere on this forum, its VERY informative.
Another scenario, spring.
If no go...
Gun doc it.

[Ares]

I'm no where near a gun tech myself so I went a little more expensive root and said screw it and dropped in a whole new pre-assembled gearbox and low and behold it's nothing to do internally in the gearbox. The BB's seem to be getting jammed in the hop up so I need to find out about those now.

[Styrak]

Have you tried other mags, like any midcaps or lowcaps? It's good to rule every possibility out.

[Ares]

I have tried 5 different types ranging from lows, mids to high and of numerous brands. I can see the BB just sticking out of the hop up an need to use an unjamming rod to dislodge it.