Jump to content


Bolt won't always lock back on empty mag question


  • Please log in to reply
11 replies to this topic

#1 yellowthunder

yellowthunder

    Newbie

  • Members
  • Pip
  • 28 posts
  • Gender:Male
  • Location:Honolulu, HI
  • Interests:Counting Electric Sheep
  • Country:

Posted 02 August 2013 - 01:38 AM

Hello all, new guy here.

I've got this issue here, when the mag is empty the bolt wont always lock back like it used to even after doing the bolt catch mod and making sure the bolt carrier is still square.  Now when I manually pll the charging handle the bolt will always lock back on an empty mag.  After doing some research here it can be a number of things.  I haven't noticed any unusual wear on the nozzle or the bolt carrier and I'm beginning to think that the blowback isn't giving the bolt carrier enough energy to overcome the buffer spring and send it far enough to engage the bolt stop.

Has anyone tried to trim down the buffer spring little by little to the point that it could possibly fix this problem and increase the dependability of this function?  I understand that the felt recoil may be reduced but I'm alright with that.

Thanks!

Edited by yellowthunder, 02 August 2013 - 02:13 AM.


#2 Rockhound117

Rockhound117

    Enthusiast

  • Members
  • PipPip
  • 95 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Music, video games, and airsoft!
  • Country:

Posted 02 August 2013 - 03:45 AM

Are you running the OEM buffer tube or a UBR? If your bolt catch and bolt carrier have no signs of wear and tear and you've done the bolt catch mod in it's entirety, meaning you bent the arm and trimmed the bolt catch to rise higher, then I would say try unscrewing the buffer tube one to two turns. I had a similar problem and it turned out the bolt catch didn't have enough time to rise up, so I unscrewed the buffer tube like Akira did in his Angry Gun Kit video. That helped me out because it gives the bolt a few extra millimeters to recede into the buffer tube, giving the bolt catch more time to rise fully.

#3 General Pickle

General Pickle

    Specialist

  • Members
  • PipPipPip
  • 313 posts
  • Gender:Male
  • Location:Oregon
  • Interests:tactical stuffs(airsoft, real steel, knives etc.), mechanical and manufacturing engineering, computers, gaming, the great outdoors
  • Country:

Posted 02 August 2013 - 10:02 AM

Interesting, I had the same issue where it wouldn't lock back every time. I did the bolt catch mod but that seemed to make things worse, then I squared the bolt off with a dremel and that seemed to give it enough space to do the trick. I found it to be a balancing game of making the bolt catch arm bent down just the right amount and having the bolt catch spring trimmed to just the right length and perhaps a few other things too. After all I've done to it I think I've got it working properly. How long did you leave the spring in the bolt catch? I found that with too much tension it won't let the catch come up fast enough, or perhaps that was also due to the bolt being rounded at the time. I wish I had a more solid answer for you, though maybe some pictures of your internals would help?

#4 yellowthunder

yellowthunder

    Newbie

  • Members
  • Pip
  • 28 posts
  • Gender:Male
  • Location:Honolulu, HI
  • Interests:Counting Electric Sheep
  • Country:

Posted 02 August 2013 - 12:43 PM

Rockhound, that sounds like a great idea!  I'll try that out.

Pretty much everything is OEM so I'm not too sure what's going on here.  It would lock back every time the magazine emptied now it may lock open after 2 to 10 dryfires.  Backing out the buffer tube might be the trick!

General Pickle, great points!

There is some wear on the bolt Carrier but not enough to round it out.  The spring I installed on the bolt catch after drilling out the hole was about 75% of the original spring detent.  Didn't seem to be much but maybe it has just the right tension to fight against the Magazine follower.  I didn't think about that!  I'll have to try both of these out!

There's really no pictures to be taken.  My LM4 is pretty much new (I purchased it 3 weeks ago) and I've only had a chance to field it once because I only have one magazine ha ha ha!  I'm getting some more soon today though!

#5 FlubberDucky

FlubberDucky

    Enthusiast

  • Members
  • PipPip
  • 71 posts
  • Gender:Male
  • Country:

Posted 02 August 2013 - 02:27 PM

I have the same problem, but only when I use my modded A2 buffer. I have the bolt catch mod as well and the bolt always locks back with the OEM buffer. When I use the A2 buffer, it seems that the gun cant push it back far enough cause its too heavy or it come back really fast slamming the bolt and not giving the bolt stop enough time to rise.

#6 netpoc

netpoc

    Enthusiast

  • Members
  • PipPip
  • 180 posts
  • Gender:Male
  • Location:Central Coast, CA
  • Country:

Posted 02 August 2013 - 04:17 PM

If you run a modified A2 buffer, you will need to use a weaker buffer spring, such as one from a WA/G&P gbbr. The buffer is too heavy and it throws off the balance when using the stock buffer spring. I was having the same problem until I made the change!

#7 FlubberDucky

FlubberDucky

    Enthusiast

  • Members
  • PipPip
  • 71 posts
  • Gender:Male
  • Country:

Posted 02 August 2013 - 10:47 PM

So where and which spring do you suggest I should buy? And what do I need to do to it to make it fit and work fine with my lm4?

#8 yellowthunder

yellowthunder

    Newbie

  • Members
  • Pip
  • 28 posts
  • Gender:Male
  • Location:Honolulu, HI
  • Interests:Counting Electric Sheep
  • Country:

Posted 02 August 2013 - 11:49 PM

Ok I did two things.  Well actually I busted my Bolt stop last night fiddling with it so I had to go and buy a new one.  The pro Shop here is sold out but by some miracle the local shop had a bunch of the improved version.  I'm really happy too because I didn't really want to go through the trouble of drilling out another bolt stop.

1.  Used a weaker spring for the bolt stop paddle
2.  Backed out the Buffer tube 2 turns

So far I've cycled the rifle over 30 times and had no failures to lock the bolt on an empty magazine.  No problems yet but we'll see!  I'll report back here if anything else comes up.  Now if I could only get more mags.  Playing with one Mag is killin me!

Thanks for all the help you guys!

Edited by yellowthunder, 03 August 2013 - 12:45 AM.


#9 netpoc

netpoc

    Enthusiast

  • Members
  • PipPip
  • 180 posts
  • Gender:Male
  • Location:Central Coast, CA
  • Country:

Posted 03 August 2013 - 06:59 AM

View PostFlubberDucky, on 02 August 2013 - 10:47 PM, said:

So where and which spring do you suggest I should buy? And what do I need to do to it to make it fit and work fine with my lm4?

This is what I am using:
http://shop.ehobbyas...gbb-series.html

Obviously the buffer is too short to use, but the spring is perfectly suited for use with a modified A2 buffer in the LM4.

#10 FlubberDucky

FlubberDucky

    Enthusiast

  • Members
  • PipPip
  • 71 posts
  • Gender:Male
  • Country:

Posted 03 August 2013 - 12:49 PM

View Postnetpoc, on 03 August 2013 - 06:59 AM, said:



This is what I am using:
http://shop.ehobbyas...gbb-series.html

Obviously the buffer is too short to use, but the spring is perfectly suited for use with a modified A2 buffer in the LM4.
Alright so if i buy that spring and i just shove it in my lm4 with the modified A2 buffer, it will work perfectly? What else would i need to do?

#11 netpoc

netpoc

    Enthusiast

  • Members
  • PipPip
  • 180 posts
  • Gender:Male
  • Location:Central Coast, CA
  • Country:

Posted 03 August 2013 - 04:19 PM

It worked perfectly for me with my modified (shortened) A2 buffer.

#12 FlubberDucky

FlubberDucky

    Enthusiast

  • Members
  • PipPip
  • 71 posts
  • Gender:Male
  • Country:

Posted 03 August 2013 - 07:29 PM

View Postnetpoc, on 03 August 2013 - 04:19 PM, said:

It worked perfectly for me with my modified (shortened) A2 buffer.
Alright well I guess I'll be ordering one of these when they decide to restock




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users