Jump to content
Airsoft Forums UK

G&P M4 acting like it's on safe when switched to auto.

Recommended Posts

Evening gents, wondering if any of you who are more technically aware than myself can help diagnose my problem.


Brought the gun to a tech to have the spring changed, learnt from him there were apparently some broken parts inside, I'm not going to pretend I remember the exact details but I vaguely remember something to do with the piston, piston head and maybe the tappet plate?


Anyway he had quite a time putting it back together, apparently the gear box wouldn't sit far enough back in the lower reciever, and there was an issue with the trigger spring.


He got it together, worked on full auto etc during testing. I haven't used it since, has been on top of my wardrobe awaiting me getting to a game.


Tried to test fire tonight, and as it says in the title, when I put the gun into Auto it behaves as if the gun is set to safety. Trigger won't budge at all...


I'm wondering what could be causing this, and if using it as is on semi would potentially cause damage it?

Share this post

Link to post
Share on other sites

is there a spring on the selector plate?


Just turned the room upside down looking for my hex keys so I could check, can I hell find them lol. ( one of the take down pins is a hex bolt, G&P and their whacky ideas)



possibly a spring jammed or a screw too tight in the safety cover or trigger area

Could feasibly be a damaged selector plate shifting the cut off lever right in the way of the switch block.


The guy they had working on it was a bit of an "apprentice" I think, I was able to sit in the small shop and watch while he kept asking the boss for help so the screw idea might not be out of the realms of possibility.


As above I cant find my hex keys to get the gun apart and confirm any of these ideas. I'll not skirmish it this morning as I'd planned to do, I'll go buy a new set of hex keys instead and try and see what's going on inside to give you guys a better idea of whats happening

Share this post

Link to post
Share on other sites


apparently the gear box wouldn't sit far enough back in the lower reciever,


I don't know how that can happen but if it does happen, then the selector plate can't move back enough to raise the cutoff lever fully. When that happens it is right in the way of the switch trolley (thanks SD), and you can't pull the trigger.

There is no harm using it on semi.

Share this post

Link to post
Share on other sites

Aye as I found on the FFR and using an aftermarket selector plate....

if the plate doesn't fully retract back far enough the cut off doesn't clear to rise above switch trolley

and it behaves exactly like the dead trigger you get when you can't fire on semi...

only problem to clear that you go auto but you got no auto ffs


The whole selector stuff is quite fine tolerance and if it is slightly out of whack or catches or worn/bent or the wonderful replace this n that crap coz all parts are made to such crap tolerances etc..... - the fine tolerances are not so great and all weird crap starts showing up


my real problem was after market plate was a tad longer than G&G dmr semi only plate on etu crap

so the plate was just hitting something inside receiver that stopped it going to full 3 o'clock

it was going 12 for semi 3 for auto but stopped at about 1:30-2:00 o'clock and the cut off wasn't lifting high enough to fire

if your selector switch is going to 3:00 ok then it isn't exact same fault as mine but does sound like cut-off is catch on switch trolley


I'd have "words" with the tech if you got it done at local shop


I feel ya pain but so should that tech guy feel some pain too

Share this post

Link to post
Share on other sites


I'd have "words" with the tech if you got it done at local shop


I feel ya pain but so should that tech guy feel some pain too

This. Don't go fixing problems that someone else got paid to fix.

Share this post

Link to post
Share on other sites

I've got a similar problem with my G&P m4... On semi auto it will do single or three shots randomly. After a few burst the trigger locks up but if I flick full auto it seems the 'clear' then is ok for a short while. A guy at the site suggested installing a mosfet. His logic was something along the lines of the gun not fully cycling on semi auto and a mosfet would help it 'reset'. To be honest he may as well have speaking a foreign language!


I'm planning to take it to a local tech to try and resolve it!

Share this post

Link to post
Share on other sites

Sounds like cut off lever isn't settling fully down to slip under the trolley

could be a mixture of worn bits or if aftermarket parts not fully 101% compatible


I really like the ol' skool trigger system but there are numerous states that have to flow & operate for it all to work sweet

one tiny bit of wear or tolerance out and you got all sorts of unreliable crap happening


Auto - the cut off is raised above trolley "lug" so she fires at will


Semi - the cut off is under the trolley lug so she lifts & disengages when sector's cam activates the lever

the trolley is lifted off the trigger sear and flies back stopping on the trolley stop...

Trigger is released just as it comes to rest it relatches back onto trolley and trolley just plops onto trigger sear


If cut off lever is worn or selector plate isn't moving correctly into each state - there isn't a great deal of margin

Then often the cut off is in between raised/lowered and thus hits the trolley lug or rail it is supposed to go above or below

Just like the dead zone - it gets stuck and should not be forced


Quite simple but very little tolerance either way

A hairline or reduced trigger mod has even finer tolerances but a pain but enlightening to how the poxy bastid stuff all works


Worse thing you can do is force it - could be a simple missing cut-off spring or very weak one - could stretch it a little to ensure lever settles better after each cycle and hopefully not need to open her all up inside

Could be a bad or worn select plate - hard to say what actual real cause is

but if trigger is locking like on safety or hard to pull (again don't force it) then cut off is not fully raised/lowered for some reason

Other problems like worn trigger sear or most likey trolley and trigger jumps off when trigger fully pulled hard - some triggers are better/worse than others


Oh yeah the trigger can be a right bitch like most stuff in ya poxy toy gun

Share this post

Link to post
Share on other sites

This. Don't go fixing problems that someone else got paid to fix.

Unfortunately seeing as I left it on top of my wardrobe for so long before checking it again I'm out of their "7 day guarantee on repairs"


To be honest I wouldn't take anything back to them as they didn't seem to be too savvy and I'd not trust them to mess it up even more...


Anyways an update, I said before that the trigger wouldn't budge on auto, however when I took the upper receiver off I noticed it moved a little bit more than on safe. Connected a battery and tried it, didn't work as before. However, pulling the trigger really hard makes it click into place and it then fires on auto...


So I'm thinking is this more of a trigger related issue?


To clarify, trigger won't go back and acts as if its on safety, a VERY hard trigger pull that would make you think you were going to break it, causes the trigger to snap backwards and it fires. On releasing the trigger you have to then repeat the hard trigger pull to get it to go back.


Trigger is however smooth as anything and very light on semi?

Share this post

Link to post
Share on other sites

No, it's what I said. Forcing the trigger makes the trolley bend and snap out of the way. Don't do it, it will wear down the trolley.


With the upper receiver off, look down on the gearbox's left side. When you move the selector, you see the selector plate moving between the GB and the body. Put it to auto, and reach down with a screwdriver or something to move the selector plate a little further if you can. If you can, then you will be able to pull the trigger easily. You don't need the battery connected for this.

Share this post

Link to post
Share on other sites

Don't suppose you know what parts they fitted ???


It is all related to 3 main parts either wear/restricting operation or incorrect aftermarket parts badly fitted

(love the TM compatibility bollox)


Selector plate - could be in compatible and fully operating to full auto

either restricted inside receiver - remove box and see if auto operates ok out of box - no battery needed but if it pops the cut off up further for auto

the plate could be not quite 101% compatible - they do vary in tolerances

it could be too long but sounds like it does allow the selector to full go to 3 o'clock

but in rare cases some plates do not have a cut out on top right - this is to ensure the rear receiver pin passes through box without hitting the selector plate

there should be loads of clearance with the top right shoulder removed but I got a d-boys box with metal plate than needed filing there as it was solid and pin just scraped or minor restricted the full movement of full metal selector plate (yeah metal - weird)


Cut off lever - some of these do vary in a few ways....

BTC spectre owners know that certain types operate the micro switches on spectre better/worse than others

On my FFR I didn't like the G&G one as it didn't seem to affix to cut off spring very straight - seemed like cut off spring mount was recessed or not sitting correctly for spring to fit straight n true - spring was angled...

Element lever was better but went with SHS cut off in the end

but all 3 types might operate differently on the selector plate raising it upwards for auto - never noticed this part as I just wanted spring to sit straight or straighter to spring/tappet plate but operated ok - well until plate was hitting receiver inside from selector plate being a smidge longer than G&G one

Think cut off lever isn't exactly worn as it probably "pops" on semi ok so the cut off lever's cam to sector gear is fine and working ok.....

But they might have fitted a new cut off that may/may not work so well on current tappet plate lifting up fully.....


Switch or trigger trolley - a new switch or partial switch trolley and might be incorrect or worn that a burr or wear/chip has started to impede the cutt off rising enough to slip over trolley on auto.....


Think the selector plate or its operation is most likely issue here - if they fitted another plate then it might have been different and doesn't fully lift the cut off far enough - the point that you file away to make an aeg to a dmr - semi only - well the cut off isn't quite lifting up far enough - heck just a further 1mm of plastic on selector plate's left off spring would of lifted cut off lever about 2mm+ maybe 3mm due to lever/fulcrum scenario type of thing

(getting technical now)


Hence me asking what few new parts were installed as I'm still learning the hard way these bastid parts are often not quite TM or current gearbox compatible

EVERYTHING needs to be fully checked for smooth operation - end of

Nah - surely that would be ok

don't simply assume it will be ok or "fine" as women would say...

(and stop calling me Shirley)


So like Samurai says see if you can shift selector or cut off that smidge more with top receiver off

probably can and it will all slip into place lovely and operate smoothly....


next is to check the selector plate in very close detail if restricted or heck if ever so slightly incorrect one that doesn't quite just lift the cut off up that last 1mm or so - if push comes to shove this "might" be able to get replaced without stripping box down...

usually you can just carefully remove replace a selector plate with a bend/twist and fingers crossed not break/snap it on a M4

(G36's - ooh they can very easily bust trying to cut corners)


Fingers crossed it is something really daft - whilst box is out see of fire select dial/lever is ok and not loose etc....

Hopefully it will be a daft stupid thing the trainee noob (no not me, I've graduated to apprentice noob recently)

something the trainee noob tech guru forgot to check or fit correctly.....

so can be sorted without opening the box - though if push comes to shove and new switch/trolley or cut off lever might be needed but hopefully it shouldn't come to this...


As Samurai says - don't force the trigger ffs - it will just get worse - you might think I'll wear it smooth

but there is a slight ramp or slant on trolley that helps the cut off lever rise up/over smoothly if need be in certain conditions...

forcing it will just wear the tip of this pointed lug away quicker and make it more difficult in the long run for semi and especially in this case auto position of cut off lever to operate - so resist the urge to whack it/force it

Yes there might a whisker of very very slight resistance on auto as the lever is guided further upwards a hairline to slip over trolley in auto

but not nowhere like having to be even very lightly forced

The whole operation or the two stages of fire modes and the actual workings of it all is a bastid if the tolerances are just a touch out


poxy mofo gun bollox - I feel ya pain I really do, my theory is that these toy guns can cause the owner himself more pain and frustration sometimes than using them on the enemy team


best of luck

Share this post

Link to post
Share on other sites

Right lads pushing the selector plate back a smidge when in the auto position does indeed make it shoot automatically as it normally should... Problem is then when I put it into semi the problem re-establishes itself meaning the plate has to be pushed back each time. Also, sometimes when switching back to Semi, semi sometimes locks up but is fixed by going to safe and then back to semi.


From what I can see the selector plate isn't going back far enough. There does look to be a cut-out for the rear body pin so I'm assuming this isn't causing the problem.


Unfortunately I don't know which parts were fitted but from what I can see down the side of the gear box ( I cant get the gearbox out of the receiver yet as I've lost my long handled screw driver for taking off the buffer tube screw) its pretty much a case of this selector plate not going far enough back. About half way along the selector plate there is a small cut out with a spring inside it, the spring itself seems to be bent with the end which is nearest the front of the gun going in towards the gear box. Could this bent spring be the problem?


Hoping this could be as simple as getting someone reputable ( or possibly even myself if its easy) to fit a new selector plate if it turns out this one isnt compatible. I know its quite a cheap one, and neon yellow if that helps in identifying it at all?

Share this post

Link to post
Share on other sites

gun spring isn't a related issue


even the cut off lever's tiny spring - this if missing would restrict semi or lever retruning from raised but not auto lifting the cut off lever upwards


The bit of good news is that I think that G&P switches if still fitted don't require the copper plate on selector plate to operate

some have prongs at back of switch - cyma's plus some others but 99.9% sure G&P are like SHS switches and no prongs at back of switch needing the copper plate on selector....

WTF does all that mean duck ffs....

Well it means nigh any selector plate will work if the same switch or similar switch is in there

a new or old selector plate in a spare box - as long as it is in ok condition it will not need the copper plate on it

don't need to remove it from selector, it actually is fine to leave on plate and moves the safety lever inside without any wear on plastic selector plate rubbing on safety cam - so yes it is not needed but if fitted to selector then leave on there if all operates ok

Share this post

Link to post
Share on other sites

Pushing back the selector plate manually was just a test so you can see that the problem is what I said in the first place. Not a fix.


If you insist on trying to fix it yourself, you need to add some material to the selector plate.

*browsing for a pic*

Here you go. Disregard that it's actually a G3 box, and your selector plate will look a bit different, the relevant parts are the same.


You need to add material to that part where the screwdriver is pointing. On the left side of the little spring there is the cutoff lever. As the selector plate moves to the right, it pushes that lever to the right, raising the cutoff, allowing full auto.

You need that to happen on smaller movement on the selector plate.

But to remove the selector plate, you need to fully disassemble the gearbox and remove the cutoff lever. (Ok, you can force the selector plate out, but you risk breaking it.)

Options to add 1-2mm of material: plastic welding, epoxy, molding in a piece of metal with a soldering rod, superglue+baking soda, etc.

Share this post

Link to post
Share on other sites

Has that plate been dmr'd already ??

looks a big gap in there and my JG G3 arrived today with free spare G3 selector plate n mag n hop - thanks GF x x x

anyway - just looked at my spare plate and blimey - that has gotta be a dmr'd plate you got there sir already

(unless TM G3's work by fairy dust or whatever)

(damn it - forgot G3 o-ring nozzle but suppose use a reduced M4 as G3 is just a smidge of smidge shorter nozzle)


+1 for pic, couldn't find a pic to show what I was on about but anyway selector is very likely issue

and if a fix/bodge can performed in situ or somehow carefully removing it then it may save more hassle without opening up box

(yes it is risky but wtf if it breaks - well it was defective anyway and new better plate required - just might be wise to open box to fit new one :))

Share this post

Link to post
Share on other sites

Selector plate is not defective. OP said the gearbox is not it its place, but moved backwards for some reason. Maybe incompatible GB, I don't know. That is the cause of the problem.


@SD: The photo is just a googled one, it must come from a "how to limit to single only" thread.

Share this post

Link to post
Share on other sites

not saying plate is defective something ain't operating as it should....


here's a picky d-boy metal plate that "can" catch on receiver pin right behind when selecting auto:




and I don't why they use this metal plate on some pdw boxes - maybe the the pin is thinner - nah can't see it

(well maybe the "arch" needs to raised a smidge more to operate on fire select switch on pdw's maybe but should of been ok-ish)

when the usual m4 box with white plastic plate will do I would of thought:




luckily the metal plate or boxes using these are quite rare and most plates have the top right cut away to clear the rear pin easily

but still the selector plate can catch or impede - ffs this box stuff is a pain....


no I'm not that clever but recently found this coz teching a std pdw box for a d-boys 416 and noted differences again in selector plate stuff

FML - does ANYTHING just fit in these toy guns and just work first time

yeah buy lonex box with lonex parts some smart ar$e says.....


but yup, reckon some reason that cut off lever is not lifting up just enough for an odd reason

and tech's like that kid give me a little hope I'm not THAT bad - depends on which day you ask me & things are going/went recently :)

Share this post

Link to post
Share on other sites

In Germany no autofire capable airsoft gun is allowed by law. Retailers there replace the selector plates with these metal ones. Maybe cheaper to make them in smaller quantities, I don't know.

Share this post

Link to post
Share on other sites

ahh yeah - that kinda makes some sense - PDW = locked to semi

well nothing a little file in top right corner didn't fix


I hate these toy gun stuff - but after overcoming problem after problem after problem and stuff "starting" to work it gets rewarding

(tell me that after I thrown all dummy's out of pram and bits of guns down the garden sitting in a heap cursing & totally exhausted from frustration)


anyway - enough about me & my odd problems...


Hopefully OP has some idea of what to look for and see if he can fix/overcome this if all else works ok

Share this post

Link to post
Share on other sites

I'm off out to the shops just now to get a long handled screwdriver so I can get the gearbox out of the receiver and some expoxy to add some material to the selector plate. Will report back and let you know how I get on gents, thanks for the help so far !

Share this post

Link to post
Share on other sites

Sorry for the delay in reporting back - motor plate screw stripped and couldn't get it out. Had the gun apart and I think the problem lies with the selector plate being incompatible. I think its an SHS re-inforced type, and the extra meat might be causing too much resistance? There were shavings of plastic coming out of the grooves that hold the selector plate on.


I put the gearbox back in the lower receiver without the body pins to hold it in place, and the selector would move the selector place as it should about 75 percent of the time. Put the middle body pin in and if I pressed the front of the gearboxs downwards, it would usually move as it should. Rear body pin goes in and it doesnt go back far enough...


Anyway I've just ordered a G&P low resistance polymide selector plate from firesupport so will see how I get on with that!


On a side not, anyone know where I can get replacement motorplate screws? Saw on a yank forum about them being M3 machine screws , does anyone have any experience with that being true?

Share this post

Link to post
Share on other sites

motor plate bolts are M3 - if they are bolts

can be self tapping screw type but most decent brands use bolts and M3 is loads of places around gearbox etc....


Gearbox bolts - M3 from small 6mm on top of v2 x 4 or 5 to the main bolts - M3 again up to 18mm long

(20mm or more is v3 motor cage bolts to gearbox)


Pistol grip to gearbox - pretty sure these are also M3's too pan head or flange type to be precise


motor plate - yup should be M3 bolts unless they are actual screws

Share this post

Link to post
Share on other sites

Cheers duck they are actually bolts, was repeating the slosh I'd read from the otherside of the pond lol.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now