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Mp7 Problem With Bolt Sticking/stopping?


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#1 Mistrael

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Posted 19 April 2012 - 06:46 PM

I've been using my kwa mp7 with king arms green gas and we .2 bb's.

I've installed the dangerwerx low power valve and, before today, it was working flawlessly.

While I was shooting it a few minutes ago it started acting up.  I would fire one bb on semi auto, and then the bolt would lock as if there were no bb's in the magazine, yet it would be full.  After this happened for a few minutes, the bolt started stopping halfway, so the bolt door is half open/closed, and neither the bolt catch nor the charging handle could move it.

I'm completely baffled as to what may be the problem.  Any input would be appreciated!

#2 Outlaw1995

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Posted 19 April 2012 - 06:52 PM

My idea is that you are using WE .2 bbs. Try getting a bag of KWA/KSC perfect .25 gram bbs (.2s or .3s are fine too!) and see if you yield different results.

Welcome to the forums Mistrael!

#3 Mistrael

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Posted 19 April 2012 - 07:08 PM

Well, they worked great until tonight.  As I mentioned before, I installed a dangerwerx low flow valve to bring the fps down  for cqc fields.
I will order some ksc/kwa bb's as soon as I can, but my first game was going to be saturday, so this is a bit of a kick in the pants.

I opened it up just a few minutes ago and discovered one of the springs that connect the bolt and the gas movey thing (no idea what that's called) has broken.  It is one of the 2 extension springs inside the bolt.  Would I be able to find a replacement at a hardware store, or would I need to order one?

#4 Outlaw1995

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Posted 19 April 2012 - 07:23 PM

You have a broken cylinder return spring. You can buy more at: store.kwausa.com or for a direct link: here: http://store.kwausa....rnspring-1.aspx

These springs hold the gas nozzle to the breach and pulls the gas nozzle back so it doesn't get in the way during firing. You noticed the bolt may stop mid-cycle, actually its the gas nozzle not being returned back by those springs that make it jam mid cycle. Buying those two springs and replacing your current ones will solve your issue.

Once again, welcome to the forums!

Edit: since you have diagnosed the problem as that, and said the we bbs you've used are fine, maybe you don't need the kwa/ksc bbs, but buy them anyway just to see how good they are and if they change your performance.

Edited by Outlaw1995, 19 April 2012 - 07:24 PM.


#5 Outlaw1995

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Posted 19 April 2012 - 07:32 PM

Return springs are out of stock on the pro shop. If you want to ask for availability, I suggest either you PM: xKingSizex, or start a new post in the pro shop section of the forums and ask when the MP7 cylinder return springs will return in stock. Or both lol. Good luck finding your springs.

#6 Mistrael

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Posted 19 April 2012 - 07:35 PM

Thanks for the help!

Evike has a whole drop in assembly for 35 bucks, so I think I'll just get that.

#7 Outlaw1995

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Posted 19 April 2012 - 07:40 PM

Can you link me to the assembly just to make sure you're buying the correct thing please?

#8 Mistrael

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Posted 20 April 2012 - 07:57 AM

http://www.evike.com...oducts_id=36454

It's obviously for the mp7, but thanks for your concern!

#9 xX Chaotic Cam

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Posted 20 April 2012 - 08:29 AM

View PostMistrael, on 20 April 2012 - 07:57 AM, said:

http://www.evike.com...oducts_id=36454

It's obviously for the mp7, but thanks for your concern!
Keep in mind that is the Low power bolt, so the FPS should be lower.

#10 jakattack1987

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Posted 20 April 2012 - 01:05 PM

both my return springs broke and the gun still works just fine

#11 gcw360

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Posted 20 April 2012 - 08:31 PM

Sometimes when only one spring breaks the cycling will foil because the cylinder is being pulled to one side.  I can't vouch for the MP7 but with my MP9 I have run on two broken spring before.  It's not a good idea but the gun should cycle so long as the broken springs are removed.  If the broken pieces are allowed to remain then the cylinder can get chewed up.  The Low Power Bolt is probably your best bet at this point IMO.

#12 Outlaw1995

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Posted 21 April 2012 - 08:35 AM

View Postgcw360, on 20 April 2012 - 08:31 PM, said:

Sometimes when only one spring breaks the cycling will foil because the cylinder is being pulled to one side.  I can't vouch for the MP7 but with my MP9 I have run on two broken spring before.  It's not a good idea but the gun should cycle so long as the broken springs are removed.  If the broken pieces are allowed to remain then the cylinder can get chewed up.  The Low Power Bolt is probably your best bet at this point IMO.
Agreed.

#13 xX Chaotic Cam

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Posted 21 April 2012 - 05:52 PM

View PostOutlaw1995, on 21 April 2012 - 08:35 AM, said:

Agreed.
disagreed.

#14 gcw360

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Posted 21 April 2012 - 07:15 PM

View PostxX Chaotic Cam, on 21 April 2012 - 05:52 PM, said:

disagreed.
Elaborate...

#15 Mistrael

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Posted 25 April 2012 - 04:00 PM

I called KWA, and they had some return springs in stock.  I should be getting them about next tuesday.

Thanks for your help!

#16 Outlaw1995

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Posted 25 April 2012 - 06:09 PM

View PostMistrael, on 25 April 2012 - 04:00 PM, said:

I called KWA, and they had some return springs in stock.  I should be getting them about next tuesday.

Thanks for your help!
No problem man! Happy to help. :)

#17 Mistrael

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Posted 30 April 2012 - 12:19 PM

Okay, this is not cool KWA...  The springs arrived today, only thing is they're for an MP9, NOT the MP7.  It's extremely apparent they are the wrong spring because they're significantly shorter than the mp7 springs.  I know for sure I asked about the mp7 springs, because I gave them the exact item number.

Also, the problem with the slide locking back still persists, and I am using kwa's own .25 bb's (Note that I have removed both extensions springs).  I will fire one shot with a fully gassed and loaded mag and it will fire, then lock the slide back.  I'm becoming quite impatient with kwa products.

Edited by Mistrael, 30 April 2012 - 12:22 PM.


#18 Outlaw1995

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Posted 30 April 2012 - 01:58 PM

Perhaps the springs actually are for the MP7. They are springs, so when you attach them to your cylinder and cylinder base, they will stretch out a bit and give the appearance that they may not be the same springs- but unless you order MP9 springs, the ones you ordered are the ones you received... (MP7 springs)

#19 xKingSizex

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Posted 30 April 2012 - 02:01 PM

Sorry for the confusion on our part. Hit up the Help Desk and submit a ticket with your issue so we can resolve htis for you.

Thank you,

#20 Mistrael

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Posted 30 April 2012 - 02:18 PM

They are absolutely NOT for the MP7.  They start stretching out (as in, they won't return to normalcy) at the normal length of the mp7 springs.

Does anyone have any ideas as to what is causing the bolt to lock back whenever I fire even a single shot from a full mag?  It happens regardless of full or semi auto.




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