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Help Me Out: KWA LM4 PTS Bolt Carrier Stuck

KWA LM4 PTS Bolt Stuck Jam

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#1 panzer

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Posted 23 October 2012 - 10:30 PM

My new kwa lm4 pts worked well for weeks since I got it. But last night, when I was shooting as usual, after a single shot, I felt the selector lever bounced from Semi to Auto, then found the bolt carrier stuck halfway in the receiver and I could not pull the trigger any more. I pulled the charging lever to see whether the bolt receiver could bounce back to the forward firing position, only to find it stuck even deeper from halfway to entirely at the end of receiver. I tried to turn the selector lever to Safe but failed, though I could still turn the selector lever freely between Semi and Auto. I pushed and pulled out the rear receiver pin in order to dissemble, but could not separate the upper receiver (possibly because the selector lever was not set to Safe, according to Manual). Has anybody experienced similar problems? Thanks in advance.

#2 Chuck S

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Posted 24 October 2012 - 04:55 AM

I believe the Forward Assist is functional on the LM4.  Can you close the bolt this way?

Even with the bolt out of battery it's sometimes possible to separate the receivers on the real M16 system by pulling both pins -- and a bit of wiggling of the receivers to get them apart.  Not sure this will work with the LM4, but probably worth a try.

Putting the selector on Safe is not required to separate the receivers.  Cocking the rifle is recommended and the rifle won't safe unless it's cocked.  Reassembly of the M16 specifies the selector on Safe.

Certainly appears there's something broken inside.  Are the trigger, hammer, and auto-sear pins still in place?  If these parts are loose in the lower receiver they can jam up the bolt carrier.

You can unscrew the lower receiver extension (commonly called the "buffer tube") and take the spring pressure off the bolt carrier or push it more firmly closed with a piece of wood.  I'd leave this to last resort.

Since you're in the PRC I assume this is the "Asia version."

-- Chuck

Edited by Chuck S, 24 October 2012 - 04:56 AM.


#3 akiraspeedstar

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Posted 24 October 2012 - 05:49 AM

If the bolt is locked to the rear, have it be half or fully, you won't be able to open the receiver by pulling only the rear pin. As mentioned pull out both pins and you should be able to separate it.

#4 R_King91303

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Posted 24 October 2012 - 12:05 PM

You can open the receiver by pushing both pins out, like Akira mentioned. Additionally, the forward assist is functional on the LM4.


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#5 panzer

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Posted 25 October 2012 - 04:59 PM

Thank you guys. It had been really hard to get any help here in PRC. I tried pulled out both pins, but receivers still could not be separated entirely. Neither can I put receivers together again. I guess I'll have to unscrew the buffer tube. I'm waiting for the castle nut wrench I ordered online the day before. I guess Chuck's right about sth. possibly  broken, as I can hear sth. small rolling in the under receiver, before trying to separating receivers. For whatever reason, the forward assistant did not work in my case.
I've never field strip my lm4 since I got it  about 2 month ago. I should have, and strengthen loose parts.
However, I am really impressed by the lm4. Professional Training Simulator is not exaggerating at all, especially in a country with close to zero possibility for a real M4.
I'll try my best, once I get the wrench.
Have a good night, my friends at the other side of the pacific.

#6 dos_Santos

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Posted 25 October 2012 - 06:03 PM

I am here in PRC (Shanghai) and wondering where I could get airsoft related gear. Can't find any.  I thought it was illegal here.

#7 panzer

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Posted 25 October 2012 - 06:38 PM

View Postdos_Santos, on 25 October 2012 - 06:03 PM, said:

I am here in PRC (Shanghai) and wondering where I could get airsoft related gear. Can't find any.  I thought it was illegal here.
Are you a local resident or visiter? Yes, it is illegal, but like a lot of other banned activities, as long as you keep low profile and not get in trouble, the cops are not to bother themselves on you. But just like protected freedom has a cost, concealed freedom too. In my case, I'll have to pay twice or even 3 times the price listed at Amazon for a whole gun (we call dog here). Separate parts are cheaper. I'm traveling to HK next week, if you need any parts or gears not in shape of a gun, you can resort to me. Guns cannot pass the customs.

#8 panzer

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Posted 26 October 2012 - 05:45 AM

I got the wrench and unscrewed the buffer tubb. Receivers got separated. Chuck is right. The hammer is broken. Fortunately, I'm going to travel to Hong Kong, the closest place to find a hammer. I'm going simply bring the entire lower receiver and get a new hammer fixed. Do you think there is any steel hammer available? The broken one is obviously alloy. BTW, since I'm bringing the lower receiver for repairs anyway. Are there anything else, you'd like to recommend, to be replaced for strengthening? Thanks. Attached File  ImageUploadedByTapatalk1351259050.874260.jpg   129.99K   34 downloads

#9 Chuck S

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Posted 26 October 2012 - 06:44 AM

I'm pretty sure the hammer and trigger are steel -- steel castings.  Sure looks like one in your photo.  Easy enough to check with a magnet.  Can't be real expensive.

With your restrictions on parts you may want to consider a spare set of fire control parts.  Hammer, disconnector, trigger, and selector.  If you can find a parts source pick up a a set of pins too.  The trigger and hammer pins are the same part number in both the real and airsoft versions.  The auto sear pin is held in differently in the airsoft using an easy to lose C-clip so a spare c-clip is recommended as well since you'll be inside the lower receiver to fix the hammer.  You can just tap out the trigger and hammer pins but the auto sear has that c-clip.  The auto-sear looks like a steel stamping and unlikely to break like your hammer.

Let us know how this works out!

-- Chuck

#10 akiraspeedstar

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Posted 26 October 2012 - 08:38 AM

Might as well buy the steel parts from Guarder (Trigger, Selector, & Mag Catch), not only does some of them work better than the original (Mag catch & Selector), but they're also steel in comparison to aluminum.

#11 -wigs-

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Posted 26 October 2012 - 03:16 PM

Wait so you never broke down the gun to clean and lube anything in 2 months?

#12 panzer

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Posted 26 October 2012 - 03:21 PM

View Post-wigs-, on 26 October 2012 - 03:16 PM, said:

Wait so you never broke down the gun to clean and lube anything in 2 months?
lube by dropping silicon from leaks around carrier.can see everything soaked when separating receivers.  But shamefully not field stripping and cleaning it for that long time.

#13 panzer

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Posted 26 October 2012 - 05:53 PM

Thank you Chuck and akiraspeedstar. I've prepared a shopping list on your advice. I hope I can find a Hong Kong store with kwa or compatible parts. I'll do some searching online before my trip. Chuck, is the "C-clip" called "Auto sear spring" in the parts diagram? Shall I also try finding some extra hopup or o-rings? btw, the hammer is steel, tested by a magnet. I hope I can find some better replacement.

#14 panzer

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Posted 26 October 2012 - 06:18 PM

And what is Disconnector? I cannot find it in the diagram.

#15 Chuck S

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Posted 27 October 2012 - 02:41 AM

Sorry, I tend to use the nomenclature of the M16/AR15 family and the LM4 doesn't always match the exact parts.  The disconnector is the Sear (Part 15) in the LM4.  It sits inside the trigger along with the disconnector spring -- er, Sear Spring (67). The trigger assembly includes the disconnector/sear.  The C-clip (209) secures the auto sear pin (52).  There are two of these clips in the rifle, the other one secures the dust cover pin.

The disconnector/sear works in the Semi mode.  If anyone is curious to see how it works cock the rifle, open the receivers, and putting something in front of the hammer to cushion its fall pull the trigger as if you're firing.  Keep the trigger to the rear and manually cock the hammer.  It'll click into the rear position.  Release the trigger and the hammer will drop onto the sear with another click.  This is the click you hear in Semi when you hold the trigger to the rear while the sights are settling back on target and you release the the trigger to reset the system.  Disconnector works the same in principle on all semi-automatic weapons, only the mechanicals differ.

I estimate the LM4 had four or five times as many small parts as the 5.56mm M4 Carbine so be careful during disassembly and don't lose anything.  US Soldiers are not permitted to remove the fire control parts from their M4, that's the job of the company armorer.  Removing the trigger and hammer pins causes excessive wear in the receivers.  Other than repair I see no reason to detail strip the LM4 either, especially looking at the dozens of parts in there.

-- Chuck

Edited by Chuck S, 27 October 2012 - 02:44 AM.


#16 panzer

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Posted 28 October 2012 - 04:52 PM

Thanks a lot. Now that I've got the shopping list, I'll try to find some parts dumps in Hong Kong. Will update what I 'll find, for any one who also need to find their supplies in Hong Kong.
I'm curious why the LM4 Asian version is illegal in US, because it's automatic and too powerful?

#17 Chuck S

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Posted 28 October 2012 - 05:47 PM

The US version is select fire as well.  I suspect the M16 upper will fit on an "Asian" LM4 lower making it a real firearm.

-- Chuck

#18 panzer

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Posted 28 October 2012 - 05:53 PM

That's interesting, even if the lower receiver has different structure? But we may never know, as you cannot have an Asian version LM4 and I'm not able to have a real m16 upper receiver.

#19 -wigs-

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Posted 28 October 2012 - 08:35 PM

The entire sizing of the recievers and other parts are different on the Asian lm4. The us lm4 was changed to meet our ATF laws and apparently the Asian model didn't pass cause they were able to chamber a real round

#20 Chuck S

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Posted 29 October 2012 - 05:31 AM

In the USA the serial numbered part is the "firearm."  Airsoft are not regulated but if the LM4 lower receiver (the serial numbered part and hence the "firearm") will accept a real M16/AR15 upper we could all get a real rifle without going thru a FFL.  The LM4 autosear functions just like the M16/M4 and we'd not only get a firearm we'd get a machine gun.  This is just how I see it playing.

-- Chuck





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