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View Full Version : Problem with my AR today at the range......


monstertodd
09-24-2010, 5:03 PM
Hey guys and gals,

Hopefully you guys can help me figure out what I did wrong today.

So I have a SW M & P 15 OR (optics ready) that I bought last fall. I've got approx. 227 rounds through it so far. Aside from a couple malfunctions, it has performed flawlessly.

The last bit of maintenance I did to it was to install a new collapsable stock. I discarded the MIL standard one that came with it and installed a magpul.

Before I get into the next part, let me apologize before hand, as I'm not exactly familiar with the terminology of certain parts.

Now, when I installed the new buttstock, I was under the impression that the buffer tube and spring had to be removed. I should have looked on you tube first but I did not. So I ended up removing the buffer tube and spring. Installed the magpul buttstock without any issue.

I reassembled everything (I thought) exactly as I had removed it. Today, I fired off about 5 rounds, and then on the 6th round, I had a malfunction. The BCG was all the way forward and the 6th round was in the chamber, but the gun would not fire. As per standard procedure, I dropped the magazine and attempted to clear the chamber by pulling back repeatedly on the charging handle. I could pull the charging handle about half way back only. I could see the round and it would go back in the chamber but it would not eject the round when I pulled back.

So what I did at this point was safe the weapon, and start to pull out the take down pins. Once I removed the upper from the lower, the BCG slid out and the round ejected. Now here is where I'm foggy on the terminology. the "hammer" was not all the way seated, and the spring and pin that sits in front of the buffer was lodged underneath the hammer down in the trigger well.

Now, when I reassembled the buffer, buffer spring, and buffer tube, I put everything back exactly as I had removed it, and I screwed the buffer tube in as far as I could get it.

So can anyone tell me what went wrong? Did I not screw the buffer tube in all the way? I didn't seem like it wanted to go in anymore. Does the buffer need to be oriented in a certain way?

Thanks for (hopefully) the help!

SJgunguy24
09-24-2010, 5:19 PM
When screwing the buffer tube in, did you press the buffer retainer down? It sounds like the tube was loose and the retainer worked out and got trapped down in the receiver.
Do every process everytime or stuff like that could happen.

Taildraggerdave
09-24-2010, 5:27 PM
The buffer tube holds down the buffer detent and spring. Screw the buffer tube in until it contacts the detent or is very close and then push the detent down with some non-marring object and screw the buffer tube in one more turn. This should put the buffer tube over the wide part of the detent with just the pin sticking up. This pin holds the buffer and spring in. Install upper to lower and check for proper operation.

Take care,
Dave

VictorFranko
09-24-2010, 5:39 PM
I've got approx. 227 rounds through it so far. Aside from a couple malfunctions, it has performed flawlessly.

Only 227 rounds fired with "a couple malfunctions" is not my idea of performing flawlessly..........

monstertodd
09-24-2010, 5:49 PM
Only 227 rounds fired with "a couple malfunctions" is not my idea of performing flawlessly..........

Well, I think this is mostly due to the magazines I'm using. They are not the greatest quality. The problems I have had have all been due to not feeding properly.

monstertodd
09-24-2010, 5:50 PM
Here are a couple pictures I took after I took everything apart and reassembled it.

G-forceJunkie
09-24-2010, 5:51 PM
What did the buffer tube stop on when it stopped turning? It should have been the skinny pin on the top of the buffer retainer (the little plunger thing with a spring under it that holds the buffer inside the tube when you remove the upper.) Screw it in untill it hits the skinny pin (you will have to push it down with a punch or something) then back it off untill the buffer tube is situated up and down correctaly, then lock it down with the nut.

Edit after seeing above pics: It looks like the buffer tube is not screwed in far enough. Hold the retainer and pull the buffer and spring out, it has nothing to do with this situation. The forward edge of the tube should be nearly hitting that skinny pin, and no way should you be able to wiggle that retainer out. I think you need to screw the buffer tube in more. Pull the buffer and spring out and take another pic, more from a downward angle right at the top of the retainer.
Now, when I reassembled the buffer, buffer spring, and buffer tube, I put everything back exactly as I had removed it, and I screwed the buffer tube in as far as I could get it.

S

monstertodd
09-24-2010, 5:53 PM
What did the buffer tube stop on when it stopped turning? It should have been the skinny pin on the top of the buffer retainer (the little plunger thing with a spring under it that holds the buffer inside the tube when you remove the upper.) Screw it in untill it hits the skinny pin (you will have to push it down with a punch or something) then back it off untill the buffer tube is situated up and down correctaly, then lock it down with the nut.

Check out the pic I just posted and see if I did it correctly. Pretty sure I did. This is exactly how I had it when I installed the buttstock before going to the range.

http://www.calguns.net/calgunforum/attachment.php?attachmentid=69931&d=1285379441
http://www.calguns.net/calgunforum/attachment.php?attachmentid=69932&d=1285379450
http://www.calguns.net/calgunforum/attachment.php?attachmentid=69940&d=1285382366

Cokebottle
09-24-2010, 6:25 PM
Hard to tell with the buffer in the tube, but it looks like you need one more turn on the buffer tube.

The edge of the tube should be on top of the pin, as close to the small part of the pin as you can get it without touching it.

monstertodd
09-24-2010, 6:41 PM
Hard to tell with the buffer in the tube, but it looks like you need one more turn on the buffer tube.

The edge of the tube should be on top of the pin, as close to the small part of the pin as you can get it without touching it.

Added a picture from the top down. Hard to tell because the top edge of the buffer is leaning more forward than the bottom that is seated against the pin, but the edge of buffer tube IS over the detent of the pin and is as far forward as it can go. I pushed the buffer back and verified this myself.

Cokebottle
09-24-2010, 6:47 PM
Take another picture with the buffer removed from the tube.
It looks like too much of the buffer is sticking out of the tube.

Is that a commercial or mil-spec buffer?

G-forceJunkie
09-24-2010, 6:57 PM
The bottom pic is the perfect angle, but pull the buffer out or at least push it in 1/4 inch then take the pic (with your finger not blocking the view of the retainer.) Check out the pic I just posted and see if I did it correctly. Pretty sure I did. This is exactly how I had it when I installed the buttstock before going to the range.

IsaacGlass
09-24-2010, 7:03 PM
Tighten the buffer tube until it touches the retaining pin. From both pictures, it looks like it's not tighten enough.

It should look like this.

http://img196.imageshack.us/img196/2586/buffret.jpg


By the way, nice looking SS, Im waiting for mines in a rag top.

1911su16b870
09-24-2010, 7:07 PM
Two things can go wrong with a change/removal of receiver extension (buffer tube). You may loose the buffer plunger/spring and/or the take down pin detent/spring. If either comes loose in your gun that can mess operation up as you've described. From your pics it looks like you've screwed the receiver extension suffiently enough into the receiver to captivate the buffer plunger and spring.

Usually they fly away never to be seen again or you're on hands and knees on the carpet searching for it. :D

monstertodd
09-24-2010, 7:19 PM
Two things can go wrong with a change/removal of receiver extension (buffer tube). You may loose the buffer plunger/spring and/or the take down pin detent/spring. If either comes loose in your gun that can mess operation up as you've described. From your pics it looks like you've screwed the receiver extension suffiently enough into the receiver to captivate the buffer plunger and spring.

Usually they fly away never to be seen again or you're on hands and knees on the carpet searching for it. :D

The take down pin detent/spring was damaged during install. A small portion at the end of the spring was bent away. Essentially ruining the spring. I cut the small portion off and reused the old portion. Still works fine. The spring underneath the buffer retention pin was also damaged, but I was able to bend it back into place more or less.

Cokebottle
09-24-2010, 7:23 PM
On the takedown pin detent spring, I always trim the spring (about 5 coils or so), tap the hole in the receiver, and lock the detent and spring in with a grub screw.

Keeps the spring from flying when I remove the buffer tube.

sleepercar
09-24-2010, 8:57 PM
It's not screwed in enough. It's pretty clear in that last picture. The buffer is coming out of the tube, and resting on the detent. However, the tube is still about 3-4mm off.