M14 feeding/firing issues & upgrades

[Tiercel]

Having issues with my CYMA M14, sometimes feeds and fires perfectly, sometimes doesn't feed at all, sometimes BB dribbles out of the barrel and only flies about 2 meters before dropping to the ground. 

I bought it brand new so no previous owner mystery tinkering, only thing I've done to it is fit a mosfet (dont ask me what, it was years ago, nothing fancy just a basic one for snappier trigger response on a 11.1 Lipo). It worked fine for half a day at NAE 2021, then started having these problems, I couldnt be bothered to fix it because taking the M14 apart is a hateful experience and havent been airsofting in ages due to work so forgot about it until now. Went airsofting at the weekend and remembered how much I love the M14 and I want it to work again. So figure rather than just blindly taking it apart and replacing things I should have a vague idea of what Im looking for first.

It cycles and dry fires perfectly every time, so I figure the problem isnt likely to be inside the gearbox itself. My initial thought is its perhaps the hop rubber/unit having some kind of issue, or potentially the nozzle perhaps not sitting/aligned right. Where to start fault finding? 

I also figure that whilst I'm in there, I may as well start upgrading some bits and (hopefully) only have to take the gun apart once. 

I'm a fairly competent DIY gun fiddler, but I've been out of the game for so long Im not sure whats good anymore. BACK IN MY DAY, everyone just went for a guarder clear hop rubber and that was that. Now theres hundreds of choices and colors and degrees. Whats the thoughts on replacement barrels? Again being old and not up to date I'd just slap a 6.03 tightbore in it and call it done, but now there seems to be loads of different options, but also struggling to find one in full size M14 length, they all seem to be the SOCOM length. So talk to me about whats worth replacing/upgrading in the Cyma M14 whilst Im in there. What I'm looking to build is a as close as possible to 350fps woodland rifle lifting .28s out to a decent range. 

 

[EDcase]

I'm certainly no expert but my thoughts on what I would check...

BB's dribbling out the barrel indicates a failed hop rubber.

Feeding problem could be damaged nozzle, tappet plate or magazine issue (fitment or feed lips etc)

As for upgrades. There are different opinions on efficiency of tight bore so maybe just look for anything the correct length.

350fps is basic performance so probably don't need to change anything in the gearbox for that. 

So the main thing to look for is a new hop rubber.  I think 75 degree is recommended for 350fps but you'll have to do some research on the favourite flavour right now ?

 

[Lozart]

Having issues with my CYMA M14, sometimes feeds and fires perfectly, sometimes doesn't feed at all, sometimes BB dribbles out of the barrel and only flies about 2 meters before dropping to the ground. 

I bought it brand new so no previous owner mystery tinkering, only thing I've done to it is fit a mosfet (dont ask me what, it was years ago, nothing fancy just a basic one for snappier trigger response on a 11.1 Lipo). It worked fine for half a day at NAE 2021, then started having these problems, I couldnt be bothered to fix it because taking the M14 apart is a hateful experience and havent been airsofting in ages due to work so forgot about it until now. Went airsofting at the weekend and remembered how much I love the M14 and I want it to work again. So figure rather than just blindly taking it apart and replacing things I should have a vague idea of what Im looking for first.

It cycles and dry fires perfectly every time, so I figure the problem isnt likely to be inside the gearbox itself. My initial thought is its perhaps the hop rubber/unit having some kind of issue, or potentially the nozzle perhaps not sitting/aligned right. Where to start fault finding? 

I also figure that whilst I'm in there, I may as well start upgrading some bits and (hopefully) only have to take the gun apart once. 

I'm a fairly competent DIY gun fiddler, but I've been out of the game for so long Im not sure whats good anymore. BACK IN MY DAY, everyone just went for a guarder clear hop rubber and that was that. Now theres hundreds of choices and colors and degrees. Whats the thoughts on replacement barrels? Again being old and not up to date I'd just slap a 6.03 tightbore in it and call it done, but now there seems to be loads of different options, but also struggling to find one in full size M14 length, they all seem to be the SOCOM length. So talk to me about whats worth replacing/upgrading in the Cyma M14 whilst Im in there. What I'm looking to build is a as close as possible to 350fps woodland rifle lifting .28s out to a decent range. 

Definitely check the hop rubber. I'd look at changing it to a Maple Leaf Macaron 60 or MR Hop 60 with the Omega nub as well. ZCI make barrels that will fit (M14 hop units have the locking clip cutouts in a different place so don't just buy any old barrel). Bear in mind that going to a tighter bore barrel WILL increase your FPS (it's happened on every Cyma M14 I've done it to). @ak2m4 carries the right sort of length but he's out of stock right now https://www.ak2m4.co.uk/internal-parts/inner-barrels/zci-inner-barrel-550mm.

To be fair, the stock inner barrel is fine, give it a good clean and swap out the hop rubber first and see how you get on.

 

[Tiercel]

I'll keep an eye out for those barrels when they come back in stock. Annoyingly I cant remember what it was firing at, or if I replaced the spring it came with  I assume I must have as its not firing at 4-500fps like most China guns out of the box. I generally stick a M95 spring in everything and find with a tightbore and decent air seals it puts out somewhere in the region of 320-330. Time to pick up a chrono again. Turns out returning to airsoft is almost as expensive as starting it in the first place  

 

[Lozart]

I'll keep an eye out for those barrels when they come back in stock. Annoyingly I cant remember what it was firing at, or if I replaced the spring it came with  I assume I must have as its not firing at 4-500fps like most China guns out of the box. I generally stick a M95 spring in everything and find with a tightbore and decent air seals it puts out somewhere in the region of 320-330. Time to pick up a chrono again. Turns out returning to airsoft is almost as expensive as starting it in the first place  

CYMA M14s don't tend to be too hot out of the box. Definitely get yourself a chrono though!

 

[slipperysquid]

Check you have active braking set, could be the motor over spinning. Do you have a 7.4v Lipo to try?
 

 

[Tiercel]

Finally stopped putting it off and took the gun apart. Considered just swapping the hop rubber and see how we go, and not opening up the gearbox because I hate it. Glad I did though as I found the problem, piston head O-ring has zero compression at all! Unsure why as it still appears to be in good condition, just... shrunk? Did the ol' "put it around the cylinder and heat the cylinder with a lighter" trick to expand it slightly, and a slather of silicone grease for good measure, and now getting a really good seal. But as I dont know how long that bodge will last Id rather just replace the lot whilst Ive got the gearbox out.

Annoyingly my local store has no suitable parts in stock. But does mean a chance to shop around for upgraded parts to replace it with. It seems the only available aftermarket piston is the Prometheus one which goes for about £30+ if you can find it in stock anywhere, dont really wanna pay that much for just a piston  Thinking of just slapping a new piston head on the existing piston as it seems solid enough. I know the piston & cylinder are unique to the gun, but are piston heads a one size fits all? this seems like a good a choice as any and says itll fit a V7, but the same item on another store says "V2/3 only but might fit others". 

Might replace the cheap nasty looking bushings with some nicer bearings too whilst Im in there.

Anything else worth doing? New gears? Motor? I dont really know much about gearsets, dont plan on using full auto ever just want a nice snappy semi auto, but not locking it to semi as I have a fear of the gearbox locking up from spamming semi too fast and needing a quick blast of auto to unlock it. 

Also turns out I already put a Modify 6.03 TB barrel in it, which Id forgotten Id done. As well as an ASG Ultimate cylinder head. Fitted the Macaron & omega nub. Will be nice to see how it shoots once Ive gotten the piston head sorted.

View attachment 106428

Also, lost that tiny spring, pinged off into the ether as I was trying to put it back on. One cannibalized clicky pen later and it works just fine ?

View attachment 106429

(yes I will of course be replacing that spring with a proper one  just wanted to test it actually fired once I'd put the gearbox back together to check it fired)

 

[Lozart]

Finally stopped putting it off and took the gun apart. Considered just swapping the hop rubber and see how we go, and not opening up the gearbox because I hate it. Glad I did though as I found the problem, piston head O-ring has zero compression at all! Unsure why as it still appears to be in good condition, just... shrunk? Did the ol' "put it around the cylinder and heat the cylinder with a lighter" trick to expand it slightly, and a slather of silicone grease for good measure, and now getting a really good seal. But as I dont know how long that bodge will last Id rather just replace the lot whilst Ive got the gearbox out.

Annoyingly my local store has no suitable parts in stock. But does mean a chance to shop around for upgraded parts to replace it with. It seems the only available aftermarket piston is the Prometheus one which goes for about £30+ if you can find it in stock anywhere, dont really wanna pay that much for just a piston  Thinking of just slapping a new piston head on the existing piston as it seems solid enough. I know the piston & cylinder are unique to the gun, but are piston heads a one size fits all? this seems like a good a choice as any and says itll fit a V7, but the same item on another store says "V2/3 only but might fit others". 

Might replace the cheap nasty looking bushings with some nicer bearings too whilst Im in there.

Anything else worth doing? New gears? Motor? I dont really know much about gearsets, dont plan on using full auto ever just want a nice snappy semi auto, but not locking it to semi as I have a fear of the gearbox locking up from spamming semi too fast and needing a quick blast of auto to unlock it. 

Also turns out I already put a Modify 6.03 TB barrel in it, which Id forgotten Id done. As well as an ASG Ultimate cylinder head. Fitted the Macaron & omega nub. Will be nice to see how it shoots once Ive gotten the piston head sorted.

View attachment 106428

Also, lost that tiny spring, pinged off into the ether as I was trying to put it back on. One cannibalized clicky pen later and it works just fine ?

View attachment 106429

(yes I will of course be replacing that spring with a proper one  just wanted to test it actually fired once I'd put the gearbox back together to check it fired)

Decent V7 gearsets are like rocking horse poo. Prometheus do (did) a higher speed set but they're pretty much unobtanium these days (if you can find them it'll be an HK import). A tightbore barrel will up your FPS, so then you'll want to knock a couple of teeth off the pickup side of the sector gear. Having discussed at length with everyone's favourite sweary tech, a Warhead motor is a good upgrade BUT you will have to heavily modify the motor cage to get it to fit. 

 

[rj1986]

Having discussed at length with everyone's favourite sweary tech, a Warhead motor is a good upgrade BUT you will have to heavily modify the motor cage to get it to fit. 

Having said that, he's now done enough of them (mine included) to have a knack of doing it, so not so risky/time consuming any more. Basically, some unlucky so-and-so has paid for all the R&D on behalf of everyone else.

 

[Tiercel]

5 hours ago, Lozart said:



Decent V7 gearsets are like rocking horse poo. Prometheus do (did) a higher speed set but they're pretty much unobtanium these days (if you can find them it'll be an HK import). A tightbore barrel will up your FPS, so then you'll want to knock a couple of teeth off the pickup side of the sector gear. Having discussed at length with everyone's favourite sweary tech, a Warhead motor is a good upgrade BUT you will have to heavily modify the motor cage to get it to fit. 

That is exceptionally impressive, and what Id love to have. But I have neither the time, patience or skill to do that myself, nor the budget to send it off to him to do ? I'll settle for a "good enough". Found some Prommy V7 high speed gears, and theyre £90 from HK, JFC. New plan is to simply get it working again and have fun shooting it at people. And then when it breaks reconsider what I put inside it ? Got a new POIM piston head, some bearings, and a Guarder V7 bearing spring guide as the stock plastic one looks like utter garbage. That should be enough to at least see how it does at a skirmish and then when something else inevitably breaks I'll figure out what I want to do with it.

 

[DerDer]

Was going to mention the Prometheus gears but someone else has covered it. They are available from Eagle six, again pricey but at least should be better postage costs.

https://eagle6.co.uk/shop/catalog/product/view/id/3965/s/laylax-prometheus-high-speed-hard-gear-set-version-7-for-m14-standard-aeg-series/

 

[Lozart]

Having said that, he's now done enough of them (mine included) to have a knack of doing it, so not so risky/time consuming any more. Basically, some unlucky so-and-so has paid for all the R&D on behalf of everyone else.

Which is fine if you want him to do it...

 

[Tiercel]

Got it back together, found the missing spring (it was somehow wedged behind the trigger assembly, fuck knows how it got there), firing at a sweet and consistent 343-345fps  on 0.2 with the hop fully off, which is perhaps a little too close to the limit for my liking, not much margin for error if the site chrono reads higher than mine. However I really dont want to take it apart again   so guess I'll find out next game day. Annoyingly turns out its a 6mm gearbox and not 7mm so the bearings I bought dont fit. All the google results for Cyma M14 gearbox say its 7mm but theyre too big. But I also dont care enough to open it up again just for new bearings, maybe if its running hot on site and needs a spring snip/change.

 

[Lozart]

Got it back together, found the missing spring (it was somehow wedged behind the trigger assembly, fuck knows how it got there), firing at a sweet and consistent 343-345fps  on 0.2 with the hop fully off, which is perhaps a little too close to the limit for my liking, not much margin for error if the site chrono reads higher than mine. However I really dont want to take it apart again   so guess I'll find out next game day. Annoyingly turns out its a 6mm gearbox and not 7mm so the bearings I bought dont fit. All the google results for Cyma M14 gearbox say its 7mm but theyre too big. But I also dont care enough to open it up again just for new bearings, maybe if its running hot on site and needs a spring snip/change.

Most if not all sites chrono with the hop set so you should be fine!

 

[Egon_247]

(apologies for the caps lock here but...)

TAKE THE HOP UNIT APART CAREFULLY AS THE WHOLE UNIVERSE HAS EATEN THE SUPPLY OF HOP UNITS UP.

I had to order mine from sixmm in Hong Kong as there's nowt in the UK. 

I mean, this was 7 months ago and I imagine you've sorted it by now but just trying to help. ??