Airsoft Canada - View Single Post - MP5 Mechbox unwinding ->lockup

Corey Darling · December 13th, 2006, 13:06

Hello

I posted a week or two ago concerning my recently upgraded MP5.

http://www.airsoftcanada.com/showthread.php?t=31667

After that upgrade - pdi 150%, torque up gears, bushings, shims, metal bb spring guide. - I decided to order a new Guarder Nozzel and Tappet Plate.

With my new found confidence in upgrading my mp5, i figured that changing 2 parts would be a sinch.

Well, Got it all back together, didnt touch anything else to my knowledge, and it wouldnt shoot the bb's the mag pushed into the chamber. I figured it was something to do with the new guarder tappet plate, or my hopup got messed up while reassembling the gun. (maybe my barrel moved in/out of the hopup unit?)

It would fire if i inverted the gun, removed the mag, and shot in single. Then i could insert a mag, and fire on full auto/semi np, although it didnt sound quite right/not the same power as before.

So i tore the gun apart again. and after reading that somepeople has to dremmle down their tappet plates, i decided to compare the gaurder to the stock.

The guarder is far wider at the tab portion where the half gear engages it. (looking from top down, its wider.)

So i put my stock tappet in but kept the guarder nozzel to narrow down the problem.

Well. Put it back together, checked timing to be "locked and at 1 oclock".

Fired and Voila! it worked, for about 10 shots before the Mechbox started to unwind, and with more trigger pulls, the whole gun eventually locked up.

Tore it apart again. The piston was cocked right back. :S Opened very carefully and let it unwind.

So for the next 3 or 4 attempts (build up, test, breakdown again), my friend and i tried to figure out what was going on with these gears.

We tried multiple timeings (half gear pin at 3-even 4 oclock) with the latch locked each time.

Still same problem. I then placed the original nozzel back in. No change.

Now instead of cocking the pistion right back and locking up, it cocks half way, and locks up. i also found this pins the tappet and nozzle right back also at the same instant. all 3 will stay that way untl i opened the case.

Any idea what is going on here? I had this gun working great a few days ago, then i change 2 parts and all of a sudden i cant get the thing to shoot. Im now on my 5th or 6th attempt, having stripped 2 of the screw locations on the top of the mech box already from tightening and loosing so much lol.

Any ideas would be much appreciated as to how to properly set this timing thing up, if that is infact the issue.

We figured the anti reversal latch wasnt locking with the grove on the bevel at the right instant, causing the whole thing to wind back and lock with the pistion just as it starts to decompress.

my dad is bringing back a p90 for me in the next few days from asia, so this mp5 will become my upgrade learning gun, im not going to touch that p90 lol, maybe except for metal bodies

Thanks

Corey

December 13th, 2006, 13:06	#1
Corey Darling Trader rating Join Date: Mar 2005	MP5 Mechbox unwinding ->lockup Hello I posted a week or two ago concerning my recently upgraded MP5. http://www.airsoftcanada.com/showthread.php?t=31667 After that upgrade - pdi 150%, torque up gears, bushings, shims, metal bb spring guide. - I decided to order a new Guarder Nozzel and Tappet Plate. With my new found confidence in upgrading my mp5, i figured that changing 2 parts would be a sinch. Well, Got it all back together, didnt touch anything else to my knowledge, and it wouldnt shoot the bb's the mag pushed into the chamber. I figured it was something to do with the new guarder tappet plate, or my hopup got messed up while reassembling the gun. (maybe my barrel moved in/out of the hopup unit?) It would fire if i inverted the gun, removed the mag, and shot in single. Then i could insert a mag, and fire on full auto/semi np, although it didnt sound quite right/not the same power as before. So i tore the gun apart again. and after reading that somepeople has to dremmle down their tappet plates, i decided to compare the gaurder to the stock. The guarder is far wider at the tab portion where the half gear engages it. (looking from top down, its wider.) So i put my stock tappet in but kept the guarder nozzel to narrow down the problem. Well. Put it back together, checked timing to be "locked and at 1 oclock". Fired and Voila! it worked, for about 10 shots before the Mechbox started to unwind, and with more trigger pulls, the whole gun eventually locked up. Tore it apart again. The piston was cocked right back. :S Opened very carefully and let it unwind. So for the next 3 or 4 attempts (build up, test, breakdown again), my friend and i tried to figure out what was going on with these gears. We tried multiple timeings (half gear pin at 3-even 4 oclock) with the latch locked each time. Still same problem. I then placed the original nozzel back in. No change. Now instead of cocking the pistion right back and locking up, it cocks half way, and locks up. i also found this pins the tappet and nozzle right back also at the same instant. all 3 will stay that way untl i opened the case. Any idea what is going on here? I had this gun working great a few days ago, then i change 2 parts and all of a sudden i cant get the thing to shoot. Im now on my 5th or 6th attempt, having stripped 2 of the screw locations on the top of the mech box already from tightening and loosing so much lol. Any ideas would be much appreciated as to how to properly set this timing thing up, if that is infact the issue. We figured the anti reversal latch wasnt locking with the grove on the bevel at the right instant, causing the whole thing to wind back and lock with the pistion just as it starts to decompress. my dad is bringing back a p90 for me in the next few days from asia, so this mp5 will become my upgrade learning gun, im not going to touch that p90 lol, maybe except for metal bodies Thanks Corey Last edited by Corey Darling; December 13th, 2006 at 13:11..