V3 trigger switch (mp5k) - the common problem

[mafu10]

Chaps,

Having been after the metal classic army mp5k for ages and not being able to get one I took a risk and bought a galaxy mp5k off the forum - contrary to the advert it was a wreck but I expected that for 75 quid anyway and I had every intention of gutting it.

Having sourced the classic army body parts I wanted and changed some bits and pieces in the gearbox, including adding a mosfet I was disappointed to find the tigger mechanism is total crap.
After around 10 fast trigger pulls on semi, maybe 2 per second the gearbox locks up, the usual flip to full auto and back fixes it as you would expect however this seems insanely bad, I've never experienced such a bad trigger. Having researched and googled my life away for what seems like days the general consensus is that this is a common issue on V3 triggers, but I have yet to find a someone who has written down a solution.

Has anyone found a way to improve the trigger reliability on the mp5k? The mosfet doesn't help too much because it would seem to be a mechanical issue which stems from the little 2 piece trigger cam pushing against the switch block and not engaging properly. I have been toying with the idea of putting in a speed airsoft upgraded trigger for an AK but at £20 I am not too sure if it would fit or make any difference so I don't want to risk putting money down the drain.

Any tips would be great, I am very handy with a dremel so I am willing to try anything. I don't think putting a new switch in will make a difference the problem appears to be inherent with the trigger design if you believe the internet.

[Lee 303]

Re: V3 trigger switch (mp5k) - the common problem

As both the AK and the MP5k use a V3 gearbox then most parts including the switch will interchange
Personally I would use a AB MosFet and with almost zero overrun it should solve your problem

[richw]

Re: V3 trigger switch (mp5k) - the common problem

I'm not sure what causes the problem but for a me a decent battery (9.6v or better) and mosfet 'solves' the problem.

[dadio]

Re: V3 trigger switch (mp5k) - the common problem

the trigger on an mp5k is a lot longer than the AK trigger and not going to help

[Scotty Dog]

Re: V3 trigger switch (mp5k) - the common problem

Could always just be the really simple niggles: Weak trigger spring, weak trolley spring, dodgy cut off lever, worn trolley ledge (for the cut off lever to grab hold of), or even the trigger contacts themselves. Do some individual troubleshooting; it'll be one of those things usually.

[mafu10]

Re: V3 trigger switch (mp5k) - the common problem

My ab mosfet and large decent lipo doesn't solve the problem. I was hoping there was some sort of modification I could do to the trigger block mechanism but I guess I will just start by replacing it and go from there... replacing all the gearbox parts until it works, or I might just bin it! It's getting to be too much hassle.

[G33m4N]

Re: V3 trigger switch (mp5k) - the common problem

I found the long trigger pull on my Mp5k was the biggest bug bear. I ended up shimming the trigger (to make it shorter ( as you said like fitting a speed trigger)) after fitting a mosfet.

The locking up and having to go to full auto and back to single, sounds like a worn trigger mech / worn cut off lever to me.

good look sound like it needs some TLC.

[richw]

Re: V3 trigger switch (mp5k) - the common problem

Don't forget to check the switch action - when the cut off lever moves up it should push the switch block up to release it and the spring should pull it back i've always wonder if its this point it gets stuck.

[mafu10]

Re: V3 trigger switch (mp5k) - the common problem

Yep I think it is when it pushes the switch block up that it gets stuck. There's hundreds of threads on forums about this problem in mp5k's but no proper solution. It just so happens the problem in mine is so bad it makes it virtually unusable. I think I will start with a new switch block and cut off lever and see what happens... I like this idea of shimming the trigger too, the pull is insanely long. I think by the time I am done with this I will have bought enough parts to have built an mp5k from scratch!

[richw]

Re: V3 trigger switch (mp5k) - the common problem

It use to be a common problem on V3's in general - I had a mate with a STAR SL8 that was semi only in the end he got it converted to full auto!

I did have the lockup problem on my G36 I remember the problem going away after fitting a AB fet but after nuking a motor with excessive semi use I removed it :P

What FPS is yours making?

[mafu10]

Re: V3 trigger switch (mp5k) - the common problem

Every time it's locking up the trigger makes a very distinctive clicking noise, I think this is the point the that little part of the trigger rides up on the block and screws up the connection.

When I got it the fps was 200. There was zero compression, seriously no resistance when I pushed the piston through the cylinder. That's now improved to 280 but I didn't change the nozzle and that's now the leaking point I need to replace when I open it up again.

I've ordered an shs trigger block and speed trigger for v3 boxes. No idea if it will fit but I'll give it a go and see if I get an improvement. Next will be a cut off lever and possibly some slightly faster gears. Failing all that it's game over.

[sj_asc]

Re: V3 trigger switch (mp5k) - the common problem

In my experience the SHS Red blocks are off spec, I ordered 5 sets for various repairs and not one of them were seated low enough, they all had to be modified to work.
This thread bears some relevance as the V3 trigger mech is the same, hopefully it can help you figure out how it works and why it might be failing. 9/10 times though it's the trolley slipping.
http://forums.zeroin.co.uk/showthrea...-issue-Gearset

[mafu10]

Re: V3 trigger switch (mp5k) - the common problem

Sniper Jesus it's funny you should say that. Having fitted the shs trigger block I no longer have semi auto. Bit of experimenting has shown up that the cut off lever isn't pushing the tigger block up high enough to cut off.
Now the gears and lever don't look worn, do I replace these or try a different trigger block? When i force the cut off lever up by hand it goes high enough to release the trigger mechanism. This whole thing has been a complete nightmare now, I'm ready to throw it in the bin.

[Scotty Dog]

Re: V3 trigger switch (mp5k) - the common problem

I used an SHS trigger block a few weeks ago on a V2 box, stopped the trigger returning after full auto; tried it with the original trolley in the SHS carrier but same thing happened. The rails must be slightly out, put an old oem trigger block back in and it was fine.

[Harlequin]

Re: V3 trigger switch (mp5k) - the common problem

I get the same deal on my Ares G36K, running a LiPo 7.4 and AB mosfet so having these doesn't solve the issue. I also get the distinctive click when it has locked in semi. I have been told it is likely to be the cut off lever from a post I put up a while back but having only been airsofting a few months I haven't got my big boy pant's on and pulled my gearbox apart