Jump to content


M18C Slide Jamming On Full Auto


  • Please log in to reply
3 replies to this topic

#1 apprentice37

apprentice37

    Newbie

  • Members
  • Pip
  • 3 posts
  • Country:

Posted 18 June 2011 - 09:02 AM

I recently picked up 2 KWA m18c second hand and am having some problems with function.  On semi, it seems to be working fine.  On full auto, it will cycle a few times and then the slide jams about 1/4 the way back.  I cannot tell if this is one the way back or on return.  The remaining gas vents from the mag.  If I re-rack it, it jams in the same spot.  When I pull the slide back, the BBU is stuck forward and as I bring the slide ALL the way back, the BBU will release from the forward position but does not retract completely back into the slide -- it stops about 1/4" short and I have to push it back with my finger.  As the slide moves forward towards the point of jam, the trigger starts to come back forward but then returns to the depressed position as the slide jams (I can simulate this in slow motion if I manually move the slide forward and back).

I can get the slide to un-jam by gently pushing holding the trigger forward as the slide returns to battery.  However, this also seems to trigger the selector to switch to safe as the slide returns fully forward.

This is happening with both of these 18cs.
I have read a little about this online and cannot find an answer - have read everything from nozzle lube to nozzle springs to hammer assembly.
It is not the mag because I have tried multiple mags.  
I do not believe it is the mag release because it is repeatable with holding the mag up.
I do not believe it is the nozzles or springs because these have been lubed and checked (both appear normal).
I do not believe the problem is in the slide because this happens with both uppers on both lowers but both uppers work fine on my other 18c lower (which has no problems).

I am wondering if this is a problem with the hammer not being reset properly, perhaps related to an upgraded hammer spring.  Since these are second hand, I do not know what the internals are but they both had upgraded recoil springs/guides and upgrade feed ramps.

#2 apprentice37

apprentice37

    Newbie

  • Members
  • Pip
  • 3 posts
  • Country:

Posted 29 June 2011 - 09:04 AM

So I finally found a post from someone in 2004 which sounds exactly like my problem and they felt it was that the hammer was not getting locked back during the slide cycle.  This makes a lot of sense and would explain why my trigger moves as I'm trying to push the slide forward and would also explain why the nozzle seems stuck in the forward position but is able to retract into the slide if I push it back.  

Could this be due to a worn sear or a hammer spring that is too strong?  I'm not sure why either of these would cause problems only in full auto but not on semi, though.  I have disassembled the hammer mech and the parts do not look particularly worn to me.

Any thoughts?

#3 Mikester619

Mikester619

    Enthusiast

  • Members
  • PipPip
  • 44 posts
  • Gender:Male
  • Location:San Diego CA
  • Country:

Posted 06 July 2011 - 04:48 PM

replace right sear(part#266), left sear(part#267), and M18c hammer(part#263)

#4 apprentice37

apprentice37

    Newbie

  • Members
  • Pip
  • 3 posts
  • Country:

Posted 07 July 2011 - 07:39 AM

View PostMikester619, on 06 July 2011 - 04:48 PM, said:

replace right sear(part#266), left sear(part#267), and M18c hammer(part#263)

I have a few extra parts and have been meaning to try these...I thought maybe the hammer spring as well.  But can you explain why you think this is the prob so I can look for problems after I swap them out?




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users