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KM4 RIS piston repair

KM4 piston repair broken

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#1 tpc2f

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Posted 23 May 2013 - 01:03 PM

I believe my piston is busted on my KM4 RIS.  I bought a new piece but when I went to open the rifle the upper pulls maybe a 1/2 inch and locks in place.  I can't dry fire the weapon to reset the piston as every time I pull the trigger it doesn't fire but rather makes a whizzing noise.  I tried disassembling the entire rifle from the grip to the buffer tube and the barrel, but had no luck.  Any suggestions on how to get to the piston?

#2 gcw360

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Posted 27 May 2013 - 10:44 AM

View Posttpc2f, on 23 May 2013 - 01:03 PM, said:

I believe my piston is busted on my KM4 RIS.  I bought a new piece but when I went to open the rifle the upper pulls maybe a 1/2 inch and locks in place.  I can't dry fire the weapon to reset the piston as every time I pull the trigger it doesn't fire but rather makes a whizzing noise.  I tried disassembling the entire rifle from the grip to the buffer tube and the barrel, but had no luck.  Any suggestions on how to get to the piston?
Hi tpc2f - Welcome to the KWA Forums.  Sorry it's taken a while to get to you, it been a very busy week of travel and participation at LC XII for KWA.  Your piston is in the locked back position.  You need to get a dental pick, or similar tool, and reach up into the hole at the base of the gun where the pistol grip attaches.  From there you will need to locate the anti-reverse latch that catches on the bevel gear.  Simply lift the latch off the bevel gear to release the piston and spring.  Then you can open the gun.

Hope this helps.





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