Full Auto "Slight" Misfeeding

[Mikeyc22]

Ill try and give as much detail as I can, yet I feel it's something simple.

Hey after upgrading my spring and piston head I also decided to change the second-hand TM hop rubber and bucking for a new TM hop rubber and bucking.

Problem is that on full auto it will fire about two shots then nothing yet the gearbox is still cycling. But sometimes it will manage lets say 5 shots. As the day progressed I think the full auto got abit better but its very hard to say... It's not my mag because I tried a friends.

Could it be the new rubber has to be "worn in" and over-time the misfeeding problem will go away, if it's the rubber causing it? When i was installing the new rubber i put the tiniest bit of grease on it then rubbed it around with my fingers, could this be a problem?

The gun sounds fine when dry fireing, it cycles fine on full auto so that makes me think its not my spring thats causing the problem. Although I did adjust the motor at one point by accident but its back in place now. Yet could that have disturbed the gears or anti reversal latch? Basicaly could a "Guarder sp100" spring cause the full auto on a TM Ak47 to go strange?

Cheers!

[Twisted Fate]

Re: Full Auto "Slight" Misfeeding

what battery is it ? maybe having a sector chip may help by holding the tappet plate back longer to load the bb

[Mikeyc22]

Re: Full Auto "Slight" Misfeeding

8.4v 3300 mAh Large type that goes in the stock. Recently blew the 15amp fuse due to accidental motor hight adjustment, its now back in place but ive put a 17amp fuse in now, just letting you know.

*edit*
Can someone show me a picture / video of the correct tappet plate position when re-assembling the gearbox? not sure the one I was was correct

[richardy]

Re: Full Auto "Slight" Misfeeding

Tappet plate has no correct position as long as it's return spring is attached, maybe this is your problem.

[Mikeyc22]

Re: Full Auto "Slight" Misfeeding

The spring is attatched. I don't think its anything to do with that, I think its more likely to be the hop up?

[richardy]

Re: Full Auto "Slight" Misfeeding

Its simple, replace the hop rubber with a new new one.

If that doesnt cure it, replace the tappet plate and air nozzle with new ones.

Thats it, thats the feeding system..

You need to do the nozzle test, which is gearbox in hand, thumb over the nozzle and hold it inand let it ping out.. it needs to do the all the way and do it rapidly.. if its slow in return or you can pull it further that it will naturally move then maybe youve got the shimming wrong or over tightened the casing on it.

If the ping test is fine replace the parts.

[Mikeyc22]

Re: Full Auto "Slight" Misfeeding

The hop rubber in it is brand new, I doubt there's anything wrong with it... but as I said before does it have to be worn in? (It's the same type and brand of rubber before)

Im pretty sure the shims are in the right place as they were before. But do they need to be adjusted when a stronger spring is put in?

What is a good starting point for re-shimming if that could be an issue?
(Where do you usually place them and how many)
Using stock tm ak47 ver 3 gearbox shims.

[badas]

Re: Full Auto "Slight" Misfeeding

Youtube is your friend with shimming, its an easy job really but i doubt it being your problem.

I would just clean out the hop and re assemble it all making sure your inner barrel isn't pushing the hop rubber out too far etc.

Ensure the airnozzle and tappet plate is getting full movement before closing the gearbox case.

I have a simular problem with my M14 but the hop rubber still needs bedding in but my ROF is sky high that hte magazines can't keep up with the feeding unless i use midcaps.

[richardy]

Re: Full Auto "Slight" Misfeeding

The hop rubber in it is brand new, I doubt there's anything wrong with it... but as I said before does it have to be worn in? (It's the same type and brand of rubber before)

Im pretty sure the shims are in the right place as they were before. But do they need to be adjusted when a stronger spring is put in?

What is a good starting point for re-shimming if that could be an issue?
(Where do you usually place them and how many)
Using stock tm ak47 ver 3 gearbox shims.

The hop rubber doesnt need bedding in to feed bbs, its a perishable item. Renewing it to new is all you need to do. The reason i suggested a new one / reassembling was incase you did anything wrong during installation.

The hop rubber its self wont stop the bbs feeding unless its blocking the barrel.

The reason full auto feeds better than single is its more violent and occasionally the tappet plate gets pulled far enough back to feed bbs.

Like i said if your not willing to do the nozzle test like i explained, please replace the tappet plate and nozzle as its really your ownly recourse left...

The gears wind the tappet plate back, which inturn pulls the airnozzle back, which feeds a bb. The tappet plates released and pushes the bb into the hop unit, beucase its on a spring. This in essence "loads" a round, a split second later the pistons released and the bb fires out of the barrel over the hop nub which is pushing down into the barrel.

Notice how the tappet plate and nozzle are it... thats all that is there to load a bb. which is why when ever anyone posts a thread now saying there gun isnt feeding im just going to copy and paste "please replace your tappet plate and air nozzle".

Thats if you mags are indeed feeding 100% fine.

You can discuse it all you like but the guys that fix theres guns are the ones who take action and buy the parts and test the results.

[Mikeyc22]

Re: Full Auto "Slight" Misfeeding

Is it bad to see this on the outside of my gearbox?
The black

[Mikeyc22]

Re: Full Auto "Slight" Misfeeding

ok taken it apart and tapet seems fine, it presses nicely with my finger.

1) Could the full auto be misfeeding due to lack of lubrication / wrong kind of grease.
2) It does full auto with hop off but it only feeds 1 or 2 then i have to let go and press it again.
3) Even though the hop if completly off is it something to do with the way it could have been put in?

I really dont know what else it could be because a sp100 spring cant cause a gun to stop working on full auto..?

[North West Outpost]

Re: Full Auto "Slight" Misfeeding

If it were me, I would take the hop rubber off and put it back on again. Befor going any further.

As a new person to taking things apart I would advise doing one part at a time and make sure everything works after each part. Other wise you end up changing several parts and a fault you cant find as the information you give may point to the wrong fault.

[richardy]

Re: Full Auto "Slight" Misfeeding

Is it bad to see this on the outside of my gearbox?
The black

in a word yes, theres a giant hole next to your bushing.. which is common if bushings arnt held in place using bearing lock, they spin and cuase wear or damage to the hole.

If the sector gear can move, how can you say for certain it isnt pushing agasint your tappet plate and slowing feeding.. if you had done the ping test originally you probably would have noticed that with the casing closed.

buy a new gearbox shell and reshim

[Mikeyc22]

Re: Full Auto "Slight" Misfeeding

Im not sure if i took it skirmishing with the metal bushings but the old spring...
So i cant tell if its those causing a problem.

I only changed the spring, piston head and hop rubber then it decides to be akward at feeing full auto.

And what do you mean by the ping test youve worded it confusingly, I tried something and the nozzle was returning in what I feel to be normal? But im not an expert..

Ill take the hop apart again just to make sure.... I guess ugh

[richardy]

Re: Full Auto "Slight" Misfeeding

regardless you need a new gearbox casing. Then reinstall the bushings with bearing lock. Then reshim. Then test the gun again.

The ping test is the nozzle test mentioned in my first post you ping the nozzle with your thumb to see how fast it returns to its resting position, very fast and smooth is normal. Some times pressing it in with your thumb you can feel it catching on the sector gear, sometimes even moving it.