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KWA LM4 PTR GBB


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Spamming the trigger semi-auto (apart from the last mag).  Apologies for the rather claustrophobic angle, I forgot the Pivotheads do that when you actually look through your optic.

 

 

Considering the trigger pull & reset is all sort of nasty compared to a RS Geissele, it does alright I think.

Edited by CKinnerley
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After a very long wait, I finally got my hands on KWA's new LM4 PTR. What follows are my initial impressions after owning it for 1 day, and using it in a few rounds of CQB. But first some pictures:  

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Has anyone tried the evo II hop up kit with the maple leaf bucking? I have a few questions about it: is it a drop in fit with no mods and does it really make a difference? I find the stock lm4 hopup to be a little inconsistent with some shots going far as 180+ then others that drop 50ft in front of me. 

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I've had the evo ii kit in mine since it came out. Bucking was a straight drop. Steel hop tensioner needed to be bent as it will send .36g BBS sky high at the zero hop setting. You need to tweak the tensioner.

 

Also, a piece of the hop tensioner arm sticks out of the hop unit some. I noticed some white residue on it after shooting some. I think BBS get caught on it when they get chambered. I dremelled excess material off.

 

Now at zero hop, I get .28g BBS sailing straight at 330+ fps past 150 feet. When BBS start dropping/ losing range, it just means that I need to clean my barrel/hop assembly. After a cleaning, I get consistent shooting range. Accuracy is pretty good in my book. I think that steel tensioner is a must have.

 

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Hello emp3ror86 we meet again :D

 

The bolt wont lock back on an empty mag with the stock KWA spring. But it will lock back on the CQB spring sent along in the package. Now after watching boobiem4h's video about the mod it seems the bolt catch mod witch has already been done on the rifle can go a bit further up a bit more with further modifcation. So it will grip more of the bolt when using the more powerfull spring. One thing I read aswell is that it might help giving the buffer tube 2 more turns outwards to give the spring more room so the boltcatch has more time to grip the BCG.

 

Plus I need to do it for a friend in the near future aswell.

Edited by Mjelnir
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Yeah I ended up closing my YouTube account and now kind of regret it as it seems a lot of people are asking where they went and needed the videos. 

 

KWA spring and CQB spring? Anyways it's correct that the newer guns KWA modified to have the charging handle functionality and they also some what pre-modified the bolt stop as well to engage better. Though they didn't do it enough as you still can bend the arm slightly to get it closer to the magazine and also need to remove some material to prevent it from coming into contact with the upper receiver. 

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Theres another mod that could be done to further raise the bolt catch. It involves sanding down part of the base of the bolt catch/firing pin assembly.

 

You will however need to sand down a part of the bolt catch as well so it doesn't wear down the bolt/piston.

 

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Okay trouble shoot part 2. Part of the problem seems to have to do with the grip. I had put a new Magpul Gbbr MOE grip on the LM4 witch went on without any problems. but when it was on the bolt would not lock back on an empty mag with the KSC spring or the OEM KWA spring. Put the stock grip back on and the bolt lock back like it should on the KSC spring but not on the KWA spring. Could this have something to do with the boltstop being pushed up or down with the new grip or is it just worn down ?

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Can you shoot a pic about the bolt catch, please?

 

The pistol grip should not have anything to do with the bolt catch. Unless the part that holds the grip and the buffer retainer gets pushed up so it prevents the bolt carrier from moving freely. Do you feel any difference with the Magul grip when you rack the handle?

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When manualy racking the bolt there is no noticable difference between the grips. Though one thing is I need to give the bolt catch a bit of time to grip the bolt. When doing a fast rack the bolt wont manualy lock back on an empty mag and just continue forward.

 

Pic of boltcatch fully extended upwards

 

IMAG0101_zps0ae3d791.jpg

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You might need to remove the bolt catch and bend its arm that connects to the bolt catch riser arm of the magazines. But you have to be careful with that because if you bend it too much it might be activated too early. You find further informations about that in my review I linked.

 

And check the bolt catch, does it move freely? Dirt might prevent it from doing so.

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is the surface of your bolt catch worn at all?

 

whats the corresponding contact point look like on the bolt carrier look like?

 

I keep on modding my bolt catch. I file little things here and there and I'm at the point where there's nothing really left for me to do. 

 

I had sanded my bolt catch at an angle...same with the area where it catches on the bcg.

 

20131015_002525-1_zpsa272f738.jpg

 

20131015_002609-1_zps8caa6a21.jpg

 

20131015_001506-1_zpsa5477011.jpg

 

20131015_001330-1_zps542ac382.jpg

 

The idea behind this mod is so the bcg and bolt catch hook to each other. As the recoil spring pushes the bcg forward, the angle on the contact area will allow for more surface area contact between the bcg and bolt catch. This makes pushing the bolt catch a little stiffer as the bolt catch will need to push the bcg back as it is "hooked". I tapered off contact points on both the bcg and bolt catch to decrease wear over time as having sharp edges on hard will eat the softer material. Contact points tapered off involve edges that rub each other when the bcg is released (to go forward) which also helps in making the release of the bolt catch a little smoother.

 

 

I run my bcg dry save for the o-rings. Those get oiled.

Edited by sacairsoftsn00py
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You might need to remove the bolt catch and bend its arm that connects to the bolt catch riser arm of the magazines. But you have to be careful with that because if you bend it too much it might be activated too early. You find further informations about that in my review I linked.

 

And check the bolt catch, does it move freely? Dirt might prevent it from doing so.

 

The Bolt does indeed move freely and is free of dirt. When bending the Bolt catch do i just bend it manually and very slowly or is there a way to it with tools ?

 

is the surface of your bolt catch worn at all?

 

whats the corresponding contact point look like on the bolt carrier look like?

 

I keep on modding my bolt catch. I file little things here and there and I'm at the point where there's nothing really left for me to do. 

 

I had sanded my bolt catch at an angle...same with the area where it catches on the bcg.

 

The surface of the bolt catch is indeed slightly worn. Maybe its just time to order a new one ?

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The area on the bolt carrier where mine catches is fine. The inside part is sharp as to maximize the contact point. The outside part is tapered/rounded as it's the area that the bolt catch grabs last when releasing the bolt. I tapered/rounded off part of the bolt catch as well. What this does is that when I release the bolt, I don't have a sharp edge snagging, cutting, and wearing down the other part.

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I had to fix a few LM4s that were having bolt catch problems. I noticed that it was more common that the bolt itself had become rounded in the area that it catches. So you might want to flatten that section on the bolt out a little bit too.

Could you post a picture of the area to flatten ? and what process did you use to do the flattening ?

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A simple steel filer will do. Brigg talked about the same area as where sacairsoftsn00py made his mod (whick looks really good). The part that gets into contact with the blt catch on your bolt carrier.

Thnx for all the help guys so just to be sure the piece that needs some aditional filing is the on the bottom left corner off the BCG as show in this picture ?

 

IMAG0105_zpsd58b8de6.jpg

Edited by Mjelnir
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