Think I found the problem - incompetent tech, Had this from early days and paid a tech (since vanished) to fit metal gears and fix low fps.
Just looked into the box through the spring retainer - no metal gears. Looks like they stripped some of the threads on the box and have fitted oversized self tappers plus one was too long so they just bent the tip out of the way.
The fitting wasn’t installed correctly and had rubbed on a spring and broken
Nothing like having your work done by an expert…
…and that’s nothing like work done done by an expert. 
I hate it when techs don’t let people know they fucked up! It happens, offer a discount or extra work/parts and let them know at least!
I have a spare J11 box that I modified to fit SHS gears, then never used as my J12 box never died if you want it.
Worth noting the J12 is a stronger box, has a bit more meat around the gears. Same in shape but the J12 has a thicker area around the bevel gear which is very very good.
Unfortunately looks like this is the only one available
https://x-forcetactical.com.au/product/jm-ak47-gearbox-j11-j12-nylon/
Ihobby seen to have the J12, with the extra material around the b bevel and the non spring mag terminals
Thanks for the tip… order placed
It’s been a day for the ARs, that’s for sure… 
Put the XM-177 back into M16A1 config… how many short arse blasters does a guy need, after all?
Then I settled on a solid polymer handguard rather than the alloy fishbone for the CYMA M4… I blame @Wombat for planting that seed. 
Looks good in Colt M4A1 carbine trim though… like a high quality Gen 9. 
Great fun playing with AR’s, it’s like LEGO.
Nope sick of that, strip it and make some of the many other models out of it 
Not wrong.
Now I have to rummage through my tubs of shit to find two front sling loops for them. 
If I’m not back in two days… just wait longer 
Looking good @Friendly_Fire
M4 is the Barbie doll for blokes
I often change them just for “seeing what it looks and feels like” lol
Taliban Barbie, likes to colour coordinate accessories…
I bet you haven’t got an A-Team collection like I have stashed away.
Blow your fuckin barbie doll out the water. I like it when a plan comes together
Well , I need help now , I’ve disabled the blowback of the Fjs M4a1 v2 jinboo edition , and now the priming , doesn’t work
what should i do ?
Not sure with that exact model but disabling blowback, look for a micro switch around that area. 
The gearbox Is inspired mostly by cyma jd100 , there are wires from the back of the gearbox ( lower than the blowback mechanism , upper than the spring follower ) you can say its a cyma m4 v3 etu mosfet version , but the mosfet escaped from the gun and ruined the fjs blowback system
Probably chopped off the wrong piece when you disabled the blowback feature.
Mag prime isn’t everything, you can live without it.
When you pull the charging handle does the mock bolt move too?
If it’s similar to the CYMA mag prime, those are triggered by the bolt cover pressing a switch, so maybe depending on how you’ve disabled the blowback it’s disconnected the bolt cover from the charging handle and no longer moves, if that makes sense.
The old JingJi SLR gearboxes were a toggle switch on top of the box that sat in a groove in the base of the charging handle and was simply pushed back and forward under spring tension from the handle.
The newer metal SLR gearboxes appear to have a button on the inside of the top groove of the gearbox and is pressed by the blowback plate being pulled further back than the piston by the charging handle.
yeah , now i’ma do some builds for this thing
What are the hardware store and electrical store modifications for these guns ( i need to build from hardware / electrical store parts ngl )
Now , can i live , without a mag prime ? Or what should i now build for my gun ( i can build blowback parts with cnc , ngl )
Mag prime isn’t a deal breaker for most.
Always handy to have some decent wire on hand and soldering supplies.
