My UTG M4 repair

So at the op I noticed that my really good UTG M4 Systema was not shooting very good at all and the fps was way down at 230 fps. So instead of using it at the op I went to my back up.

I took the UTG apart all the way down to the dissembling the gearbox and found a couple broken and worn out parts. Its a pretty big deal to take this thing apart since it is a systema gear box and retails between $250 and $300 just for the gearbox itself. So I was under immense pressure to get it all back together and working right. Ohh did i mention that ive never taken a gearbox apart? I went ahead and replaced a broken spring guide with a guarder Ball bearing one. Found a worn nozzle so I got a prometheus replacement and just for good measure I replaced the spring with a new M120.

After a long and tiring ordeal I managed to get the gearbox and gun all back together and it seems to be working properly. Its shooting right at 400 fps on average and straight as an arrow.

congrats

Thanks for the help CDR I was lost in the beginning for sure.

Did you fix the jamming problem?

Yes Im an idiot and set the nozzle behind the tappet plate so it couldnt move. Once I saw another guns nozzle moving I smacked myself in the fore head in classic duuuuuuuhhhh style and took the gearbox back apart set the nozzle in the propper grove in the tappet and low and behold it worked!!!!!! I felt like an idiot but whatever im learning. I feel completely confident now with gearboxes after taking mine apart 20 times including the trigger assembly which decided to fly out of it on one of my teardowns. I still dont get how to shim a gearbox properly, how do you know when youve got the play out of the gears? How do you feel the play???

close the gearbox with just the gears (without the tappet plate and cylinder assembly) screw a couple of screws on the gearbox to make sure its all the way closed and push each gear from both sides and see how much play it has. also from the opening where the cylinder go you shoud see the gear. turn it with your finger and make sure they are not too tight when u add some shimings. if u have any questions feel free to call me.

Ahhh ha that makes sense. I think im gonna tear down my JG m4 now and shim it up and replace the piston. Im sure its getting pretty worn my now. If I replace it now I wont have to deal with a breakage on the field or more parts breaking all at once.

My next endeavor will be a barrel and hop up on my JG m4. The gun has amazing range and is a ton of fun to play with so I think im gonna get either a 603 prom barrel or a PDI 601 with a firefly bucking. Any other suggestions would be great!!

Well I'm glad it all worked out!!

Thanks again Medic for the great gun I love it.

Sooooooo the first day out with the repaired gun this is what I ended up with.

[You must be registered and logged in to see this image.]

I'm not a systema expert...but is it supposed to look like that?

Funny, no

Are you able to figure out what happen?

Airsoft god (CDR) any input?

bad timing between gear and piston....bad shim job.....batt to hot for the set up .

More like bad luck I believe. The shimming is perfect and the battery is a 7.4 lipo. May be a timing issue I didnt think there was a way to set the gear timing maybe I missed somethin there.

Any input is welcome.