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V2 trigger assembly problem

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Got one here that I've not seen before, but am wanting to ask t'internet before just replacing the trigger switch assembly.


I've been working on a friend's M4 for a while now and EVERYTHING seems to have needed replacing at one point or another, it seems that it was originally held together with nothing short of hopes and dreams.


The current thing that I am looking at faulting is the trigger switch assembly. At first I thought that the gearbox was locking up, but in actual fact it seems that when firing on semi the moving item (the shuttle?) seems to sit just above the trigger after being knocked by the cutoff lever. This means that the shuttle sits too high to be engaged by the trigger itself, so it's a mechanical issue per se and not electrical. I've not checked for wear on the back of it, but has anyone else come across this before?

and know of a fix?


Google only seems to turn up overspin, locking up and poor trigger drill.

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Do you mean the shuttle or trolley - as it lifts of the trigger it flies backwards

but does it jump over the trolley stop - often square-ish shaped thingy majig dooberry


it should fly back but should remain in front of square stop and then the trigger should relatch onto it


first thing to check is the trolley spring fitted correctly

incorrect fitting of spring could impede the tappet plate slipping over it

and also it effectively pulls the trolley back but also from that top front tip or log the spring fits onto

it pulls backwards and exerts a downward force at the rear of trolley where the trigger's sear relatches again


both the springs of trolley and tappet do have a correct way round to be fitted so that they operate correctly and smoothly


So check the spring is operating correctly.....


The trigger or trolley could have wear - some triggers can be a little shorter/longer than others

even cut off lever can be different too and when you start replacing one item you need to check these poxy aftermarket parts all work perfectly together which often it is no big surprise that they don't always play nicely together and need so discipline from a file or stuff


anyway check some stuff out


check operation by removing cylinder/piston spring etc.... in a bare assembled box but with gears etc like you do with shimming

pull trigger in semi and wind sector over to pop the trolley up & off the sear flying backwards - wind sector a bit then check it relatches


if you try to force the cut off lever back where spring goes from selector plate you will likely pop cut off too high and the trolley will jump backwards but be too high and jump over the stop on v2's so don't test trigger switch operation by popping the cut off lever by selector plate on v2's


V3's have a larger/stronger stop built into 2 halves on gearbox and can not jump over trolley stop like V2's can

so v2's you test operation by rolling sector gear to pop it off on semi


hope some of this makes a bit of sense


there are numerous issues and posts about trigger problems - 90%+ of actual trigger problems are semi related

coz auto nowt really happens - just a simple on/off of circuit

semi though - all hell breaks loose with the mechanics of the design coming into play and tbh there is a fairly fine line of it all working or not


often the final stroke of the trigger pull the metal sear is just on the very bottom of trolley, too much and it don't lift up easily & quickly to fly back also a high amount of sear not only requires more lifting of trolley but when it relatches the trolley's ar$e gets pushed up higher when relatching at trolley stop



too low and she will jump off trolley at end of trigger pull so a new trolley or complete switch or another trigger itself may be needed


the whole bloomin process is a ball ache when it don't function correctly


actual pinpointing what n why takes a little time and common sense but across the internet it is hard to sometimes diagnose stuff 101% correctly first time due to slight interpretations & descriptions being a tad different


a post is here to maybe shed some light on numerous pita issues:




and yes they are a pain in the ar$e

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Many thanks for the reply, I couldn't find a specific term for the trigger trolley, as it's not something that I'd ever encountered a problem with before.


I'll re-check the spring on the switch assembly and go from there. I did notice that the trigger was slightly worn on top, so I might be able to extend with a little metal epoxy and go from there.


This could well be it, as it seems that after going through a semi cycle, the trolley sits ever so slightly higher, so the trigger just passes underneath. Bloody thing.

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Well if all else fails try some other bits n bobs from a spare parts box


honestly just the trigger itself can vary on the sear height

trolleys can wear on the underside


the spring needs to be fitted correctly - often it don't affect it that much but the spring needs sit central so tappet plate's groove flies over it smoothly

different boxes vary so much sometimes and when you throw certain aftermarket parts into the mix - some new parts work better than others


often shs switches are thought to be very universal

if you are not ok with resoldering a brand new switch often you can just use trolley on old switch if contacts are ok


triggers - in past I have replaced a brand new d-boys m4 trigger that was so close to just jumping off trolley at full pull

replaced with a crappy old spare trigger and it was like I fitted a brand spanking new one than an old battered one

APS trigger's from TaiwanGun have a larger lug/sear than other M4 triggers I have noticed


and finally if all else fails you could order some new bits up and whilst waiting for them to arrive

with a bit of epoxy - JB Weld some plastic/metal glue on some new material and have a go at hairline trigger mod

it is do-able but a bit of a pain at first and involves glue - waiting to dry - file - test - file - test - file - test etc.....


yup but you really get to understand the whole operation a little more - a bigger pita at first but often you can get an iffy trigger working better and sweeter


Not done a tutorial as I have done a mix of a few guides and altered it a little to what suits or works for - so far....

the outline is a copper bit from an old heatsink (dead ps3 ihs - but a bit of file-able metal about 1.5mm - 2mm thick)

then an L shape piece of plastic at rear of trolley - the L is not really needed - just needs a piece to in front of stop but a larger L shape just sticks better

JB Weld clear easy mix 2 part epoxy in twin tube syringe - rest is time messing about....

anyway a pic showing some more info:




Red/yellow area on std trigger is where you might add material to reduce the max full trigger pull

works better on trigger than box I have found plus most modding is on trigger/trolley so if all else fails just replace with new std trigger/switch/trolley and you go back to "normal" trigger setup if all else fails


all you need is a craft file to fine tune and get it just right to pull - lift - relatch etc....

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I thought I'd reappear instead of taking advice and pissing off haha


In the end, the spring had nothing to do with the issue, and I believe that the root cause will have been a worn switch trolley or the replacement shell allowing the trolley to sit a bit too far back.


To repair I filed down the trigger to have it sit further back, almost the opposite of the hairline trigger you mentioned. In addition to this I sharpened up the top of the trigger, the surface that interfaces with the switch trolley, and that seemed to work a treat. Similar process mind, in that it was a case of file/test/repeat.


Either way, as soon as I got it working the tappet plate snapped when trying to reassemble. Finally working and sounding beautiful now after a complete overhaul, my buddy doesn't know the pain I've been through with this.

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Well well done anyway - could of added material to rear of trolley to stop trolley going too far back

but then you may have had to check the COL drops down etc....

(probably more work if gluing stuff etc...)


But you got a general idea of how it all works and just how fine some of the tolerances are

You would think this TM Compatible stuff would just work - but nope not always


A new trolley or trigger might have fixed it also or not quite and still might have needed some adjustment with replacement parts

But as it wasn't functioning correctly you had nowt to lose by making a few adjustments - kudos for getting it working

soz about tappet plate - I feel ya pain on these damn boxes....

Ya fix one thing and another wheel somewhere else falls off - damn it


ps - cheers for update, didn't quite diagnose it exactly but some suggestions for you to suss it yourself

well done again sir

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Like I'd eluded to, I've always worked on my AEGs and would say that I am capable of more than just basic repairs and upgrades. I've also taught friends to do the basics too; I am contemplating a DSG build, just to see if I can pull if off.


This rifle however has been the bane of my life. Glad it's finally off the workbench. I am paranoid that once he gets it back that it'll shred a piston.

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lol - its them bastid boxes you learn the most on I feel


don't matter if it busts in the end coz it was a crap box anyway

but I feel if you can get a pile junk to run better - if at all....

then that to me means more than just buying everything high end & getting working Lonex shell, gears, col, piston etc.....


some of the cost effective stuff I'd buy again and some I'd wouldn't touch if they gave it away

sorting the wheat from the chaff as they say and getting stuff to run effectively - even with some fine tuning/modding is the tech side of things

otherwise in my opinion you are just assembling stuff - not really technical or engineering in my mind


Guns - well they do wear and break - some worse than others

stick a crappy lame std G&G 18k motor in there - he'd have to go to 14.4v or more to shred that lame motor/box

or tell him to just mount on a wall coz you ain't fixing that pile of crap again


well done fixing ya toy gun

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