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m4 not firing

eX0ps^SIME

By eX0ps^SIME,
in Technical Discussion

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Tommygunn

Tommygunn

Posted
Posted

Christ!

Let me clear this up a bit. Remove motor and pistol grip. As has been badly mentioned, take a paper clip/stiff piece of wire and hook the end with a pair of plyers. Then hook it under the anti-rev latch and pull to release the spring tension. It will NOT jump out of your hand!

 

Secondly, you will NOT need a new spring, that is a ridiculous thing to say. True, springs like to be in a state of relaxation as far as possible blah blah, but this is going to do sod all to your spring.

 

Here's some things to do:

You didn't say what type of battery cells you were using so I'll guess you are using an AF (17mm diam) mini type pack. If this is the case I would suggest trying to borrow somebody's large SubC pack and seeing if it cures the problem. SubC packs due to their physical size, in the main, have far superior internal resistance/discharge characteristics which give far greater punch than smaller cells - often a cause of lock-ups.

 

While you have the motor and grip removed, and the main spring relaxed, check the shimming. Do this by attempting to rotate the Bevel gear through the motor hole in the gearbox. The bevel gear should rotate with virtually zero effort and then at some point start to build in pressure as the Sector gear engages the piston and compresses the main spring. If, however, there is any difficulty in rotating the bevel i.e. excessive friction, then you have a possible tight shim job which is draining your battery and preventing it from getting over that final hurdle.

 

If it turns out your shims are a problem then follow my guide here, towards the bottom of the thread:

http://www.arniesairsoft.co.uk/forums/inde...c=67255&hl=shim

 

Take the piston, spring and spring guide and with a screwdriver dropped through the inside of the spring guide attempt to compress the spring guide and spring into the piston. You should get the spring guide base to within about 5mm of the edge of the piston which should give plenty of room to allow for the trip point of the Sector gear and piston. If there is any stiction/other abnormalities beyond the normal tension of the spring then this could be another possible problem and needs investigating.

 

Screw down the gearbox with just the piston(no spring, guide, cylinder etc) then try pushing the piston back and forth, with a long screwdriver or similar, along the piston rails to check for any abnormalities/friction.

 

Try some of that and I'll have another think.

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Stealthbomber

Stealthbomber

Posted
Posted

What Tommygunn is thinking, but hasn't said outright, is that usually there's no such thing as a "gearbox lock-up" or "gear jam".

 

What actually happens is that, if you are shooting in full auto, the gun relies on a certain amount of momentum to allow it to complete the firing cycle.

If you stop firing just before the gun is going to shoot you can sometimes find that the battery just doesn't have the oomph to start the gears turning again.

This used to happen a LOT in my CA MP5 when I was using it with mini batteries.

 

All that's needed, usually, to free up these "jams" is to connect a bigger battery and pull the trigger!

 

One of my top secret, pro airsofter bits of kit is a large to small battery adapter.

Usually it's guns shooting with small batteries that lock up like this. I hook up a 9.6v 3600mah large battery to the gun and it turns the gun over no problem.

 

Did the battery come as part of a deal?

I suspect it's as cheap as a discounted very cheap thing made of bits found at the local tip.

Get a decent battery and charger.

 

Also, don't worry too much about leaving your spring compressed. I do it all the time. As long as it's only for a day or so you should be fine. Leave it like that for a month and you'll be in trouble though.

 

Of course, if you had a gun like an ICS M4, TM FAMAS or one of the L85s you wouldn't have this problem because those guns have a lever you can press to decompress the spring.

 

Incidentally, I gotta say that I've never managed to successfully unhook the anti-reversal lever with anything like a paper-clip.

Firstly, there's very little room to get anything in and, secondly, these jams only occur when the spring is highly compressed. At this point there is a lot of force on the anti-reversal and a paper-clip just bends rather than unhooking the latch.

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Tommygunn

Tommygunn

Posted
Posted

Yeah, I havn't used a paper clip but a piece of stainless wire(for my KSC pistol mags) at least a third thicker or twice as thick(havn't measured) with a right angled hook about 3mm long and it works a treat.

Actually, like Stealth says, it is not highly recommended unless your in dire straits because in all likelihood the Sector will reverse and batter the back edge of the Tappet 'shark fin' and since it has no forward give could possibly snap.

 

If you can't release, or don't want to release the gearbox in the above way, then the safest way to do it is to stick a screwdriver in the back of the spring guide prior removing the gearbox case. You must put firm downward pressure on the screwdriver with the handle butted up against the gearbox and carefully remove the gearbox half to prevent the spring from jumping out. When the gearbox half is removed hold the cylinder and carefully unhook the spring guide under control of the screwdriver to release the spring tension. Beware!

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tgrillo

tgrillo

Posted
Posted

I'd be more worried that AEX would break my gun, rather than me screwing up haha.

 

Not many techs can be trusted. Do it yourself, so you are sure everything is.

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No Mercy

No Mercy

Posted
Posted

You Sir have no idea what is going on

 

You spring is Not Am teh Ub3r Br0k3 OK!

 

 

How about you listen to us and find a bigger battery

 

 

Ie. Your battery Su8ks

 

Your gearbox hasnt been opend up so theres nothing wrong with your Spring guide and that

 

its your battery or fryed wiring

 

I think its your battery

 

nm

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Dusk

Dusk

Posted
Posted

Simple: 1. Put a 9.6 large or a lipo in there... it'l unsieze it in a jiffy..

 

Or!

 

Open your gearbox and reshim it, and put the spring in the right way and you wont have any problems. taking apart a gearbox is so simple its funny how people are so scared of it....

 

Just make sure your working on a white mat so you can find the parts when your compressed gearbox shoots them everywhere.

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Dusk

Dusk

Posted
Posted

Works for me 90% of the time im feeling lazy and dont feel like opening it up :P

 

Risk anything? ITS A $100 GUN! at AEX your going to be putting more money into the gun that is still, not as reliable as a TM. so... $200+ for a gun that broke on you and you had to fix that will break again isnt risking? Buy a TM and whalah! You will have left the game by the time it dies on you....(IE death hopefully)

 

Dude, just do this...

 

Unscrew your 2 bottoms screws from your hand grip, detach wires, remove motor, (dont loose the silver shim, kinda important), remove two screws further into the grip and then get a dentist tool or something and pull on the little latch thats engageing on the exposed gear. Then repeat what i said in reverse to reinstall everything.

 

Takes 5 minutes at most, no parts flying everwhere, 5 big parts in total. Not hard to do at all and will save you alot of money and time.

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