It just won't shoot semi...

[shadow_matter]

I am working on a CA MP5 that had a host of issues. Last to go was the selector switch wasn't positively clicking into semi or safe spots. That was fixed with the installation of a new CA selector switch and systema selector plate.

Remaining problem is, it still shoots full auto when in semi. Safe works fine, it's a solid click into semi (selector switch AND plate) but it will fire full auto.

I noticed that there was a fair amount of gunk/(corrosion maybe) on the metal contacts in the triger unit, I cleaned these up as best I could then buttoned it all up. I also payed special attention to not over tighten the cut-off lever, ensuring smooth movement with the palte.

I guess the last two things could be the cut-off lever istelf (looked fine, no noticable wear) or the trigger unit.

What do you guys think? Does anyone have specific experience with this problem on CA's?

[Skladfin]

does it shoot burst/semi when you pull the trigger really fast on Semi?

I had the same problem and a this really helped me out:

Okay.. I guess that settles it. There's nothing wrong with the cut-off lever. The problem is with the trigger pull - you're feathering it.

With a real gun, the trigger sear will release the hammer, and fire the gun, the same way regardless of the trigger pull. Real gun shooters feather the trigger so as not to jerk the gun and spoil the aim.

AEG triggering works differently. If you feather the trigger, the switch slide moves just enough to make contact with the contact prongs (sending power to the motor and cycle the piston).. BUT not forward enough for the cut-off lever to disengage it. The AEG will keep firing until the vibration makes you do pull the trigger all the way or let it go.

The most immediate solution.. is to change your triggering habit. Always pull the trigger all the way.

As already mentioned, another solution is to spread the contact prongs wider apart so that it the switch slide has to go all the way forward (which, just the same, requires the shooter to pull the trigger all the way) before making contact.

That's it.

hope that helps

[rustysniper]

If the cut off lever is properly adjusted....and you have a new selector lever as well as selector plate....then there are two things left which affect "select fire".
1. the fitment of the pistol grip/receiver over the gearbox. A snug fitting receiver can push on the selector plate and deflect it's travel. I had this happen with an ICS as well as a CA metal receiver models. Was remedied by changing selector plates multiple times until I found one the moved freely within the receiver.
2. Switch contacts. Unfortunately the two little brass contact prongs tend to get bent a bit (or wear depending on age of gun and voltage of battery) so that the contact for single and auto is not proper. The gun will usually just fire auto then. The only solution is to replace the switch assembly.
I have also had this issue on other V2 gearboxes as well.


That's my 2 cents worth..........

[Crunchmeister]

I had the same problem with my JG MP5. When I replaced some internals, I also swapped the cutoff lever and the problem is now a thing of the past... And it looked fine to me as well, but replacing it fixed the problem.

[shadow_matter]

I am exerting proper, full trigger pull. As I depress all the way in semi, it cycles in full-auto in the exact same fashion as when the selector is in auto.

The owner has communicated that this is a new problem in over 3 years of ownership, so I really doubt it's a bad combination of the stock body and gearbox. I have already verified that the selector plate moves freely with body installed.

I may have to get a cut-off lever to see if that is the issue. I hate doing these kinds of repairs, especially for other people; purchasing parts without any sense of confidence, waiting for it to come in and hoping that it will work.

Uncertainty is frustrating.

[m102404]

A sure fire but no-return fix is to elongate the notch of the selector plate that pushes the cutoff lever out of position in full auto.

Trim 0.5mm off of the left side of the notch, so it won't touch the cutoff lever until it moves a little bit further to the right...(looking down on the left side, nozzle pointing to the left)

Whatever setup you have is tweaking things a bit out of position.

If you trim too much...you'll have semi-only...so go slow, cut little, test fit often.

Best of luck,

Tys