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Posted: 1/21/2011 10:02:54 AM EST
[Last Edit: 1/21/2011 10:04:43 AM EST by FatPants]
Hey yall,

I'm having an issue with my first ar build. The buffer retainer is beating up the face of the buffer. I read about this in the faq on this site and it mentioned that the upper could be sitting too far forward in the lower, the barrel extension could be too short, or the lower could be out of spec.

My upper sits nice and tight into the lower, no noticeable gap at the rear. My bolt carrier sits exactly flush with the rear of the upper.

My concern is that the hole for the buffer retainer is too far back, making the buffer ram into the retainer as it pushes the bcg forward. When I drop the upper onto the lower, the rear of the bolt carrier touches the buffer ever so slightly.

My question is, short of buying another lower, is there any other fix for this? Im considering chucking the buffer into the lathe, and relieving the edge of it just a hair to allow it to make better contact with the carrier, and avoid it getting beat up by the retainer.

Thanks for your help!
Link Posted: 1/21/2011 10:06:49 AM EST
Are you sure it is the buffer retainer? The back of the bolt carrier could have a sharp edge and be damaging the buffer face also. The damage looks very similar in both situations. If when you close the upper on the lower the bolt carrier contacts the buffer, it is most likely not the retainer doing the damage.
Link Posted: 1/21/2011 10:19:21 AM EST
I'll give it a second look when I get home from work, but it looks very consistant with the retainer. I'll update when I get home.
Link Posted: 1/21/2011 10:28:21 AM EST
Post pics if you can.

If everything fits properly, the BCG should keep the buffer off of the buffer retainer pin when the receiver halves are assembled.
Link Posted: 1/21/2011 10:53:38 AM EST
Originally Posted By KBAD:
Post pics if you can.

If everything fits properly, the BCG should keep the buffer off of the buffer retainer pin when the receiver halves are assembled.


I'll definitely snap some pictures.

The bolt carrier does just barely make contact with buffer, but I don't think its enough to keep the buffer from hitting the retainer.
Link Posted: 1/21/2011 12:06:43 PM EST
[Last Edit: 1/21/2011 12:08:20 PM EST by FatPants]
http://i69.photobucket.com/albums/i41/FlatFender_2006/IMAG0412.jpg

http://i69.photobucket.com/albums/i41/FlatFender_2006/IMAG0413.jpg

http://i69.photobucket.com/albums/i41/FlatFender_2006/IMAG0415.jpg

http://i69.photobucket.com/albums/i41/FlatFender_2006/IMAG0411.jpg

http://i69.photobucket.com/albums/i41/FlatFender_2006/IMAG0417.jpg

This buffer was brand new yesterday, and after firing about 200rds, this is how it looks now. I ran my finger all over the rear of the bolt carrier, and I cannot find any sharp edges that would be consistent with that.

Its hard to tell from the picture, but yes, the buffer tube is holding down the edge of the buffer retainer.
Link Posted: 1/21/2011 12:12:16 PM EST
Link Posted: 1/21/2011 4:38:19 PM EST
[Last Edit: 1/21/2011 4:44:31 PM EST by j3_]
Takes a little work but I made an offset buffer detent pin to go in a old Sendra lower I have to stop that from happening. Its held straight by a notch in the bottom of the buffer tube I filed to a depth that timed out with the stock tube aligned correctly and not screwed in to far that it would stop the upper from closing..


Before that I had one of the M16 clinic polymer stick on pads on the buffer so it beat up the little pad instead of the buffer.
http://www.brownells.com/.aspx/pid=19699/Product/AR_15_M16_AR_10_AR_BUFFER_PAD
Problem there is they are almost as much as a new buffer, price seems out of line to me for what they are.
Link Posted: 1/21/2011 6:28:00 PM EST
[Last Edit: 1/21/2011 6:29:36 PM EST by FatPants]
I figured since the buffer was already damaged, I couldn't make it any worse. I wont have access to the lathe for a few weeks, so I broke out the dremel, and offset the buffer. Going slow I was able to make it "serviceable". Not pretty, but if it functions, I'll keep using it.

I'll probably end up replacing the lower at some point, but for now, I want to shoot the hell out of this rifle.


It looks off-set a bit in the picture, but I think its the lighting. Its pretty well centered for doing it freehand.
http://i69.photobucket.com/albums/i41/FlatFender_2006/IMAG0420.jpg
Link Posted: 1/21/2011 7:01:25 PM EST
Got to ask who made the lower.
Link Posted: 1/21/2011 7:55:38 PM EST
Originally Posted By j3_:
Got to ask who made the lower.


...rguns...

I know they dont have the best reputation, and I see why...This was a budget build, and I couldn't argue with a $60 lower. Ive got a line on a spikes lower I may pick up this week.
Link Posted: 1/21/2011 8:22:40 PM EST
Originally Posted By FatPants:
Originally Posted By j3_:
Got to ask who made the lower.


...rguns...

I know they dont have the best reputation, and I see why...This was a budget build, and I couldn't argue with a $60 lower. Ive got a line on a spikes lower I may pick up this week.


If it's destroying buffers, save it for a dedicated rimfire build.
Link Posted: 1/21/2011 9:40:40 PM EST
Link Posted: 1/22/2011 2:06:01 AM EST
Or, you could just remove the buffer retainer pin all together. It's only needed when the receive halves are separated

You'd just have to hold back the buffer with your finger while you pivoted the upper to the lower. Badda bing
Link Posted: 1/22/2011 3:33:40 AM EST
Originally Posted By KBAD:
Or, you could just remove the buffer retainer pin all together. It's only needed when the receive halves are separated

You'd just have to hold back the buffer with your finger while you pivoted the upper to the lower. Badda bing


This would be the easiest fix ... like KBAD said the retaining pin is only there to keep the buffer flying out when you separate the two.
Link Posted: 2/7/2011 2:42:07 PM EST
So, just a quick update for everybody. My lower receiver was definitely out of spec. I found a great deal on a new Spikes lower locally today, and just swapped over my lower parts and re-assembled the rifle. Not only does the buffer contact the bolt carrier, I can definitely feel it when the two go together.

Also on an unrelated note, with the old lower, my safety switch would not go completely vertical when switched to the fire position, with the new spikes lower, it goes completely vertical AND it snaps into place better than with the old lower.
Link Posted: 2/8/2011 11:19:40 AM EST
Originally Posted By FatPants:
So, just a quick update for everybody. My lower receiver was definitely out of spec. I found a great deal on a new Spikes lower locally today, and just swapped over my lower parts and re-assembled the rifle. Not only does the buffer contact the bolt carrier, I can definitely feel it when the two go together.

Also on an unrelated note, with the old lower, my safety switch would not go completely vertical when switched to the fire position, with the new spikes lower, it goes completely vertical AND it snaps into place better than with the old lower.



I hope you have contacted rguns.They need to make that right one way or the other.
Link Posted: 2/8/2011 11:48:15 AM EST
[Last Edit: 2/8/2011 11:49:10 AM EST by 1IV]
$6 fix
Take a detent. Vice it and file it down.

See pic. Been there done that. It puts the pin a little higher. And prevents chipping.
Try it.

My drawing is exaggerated.
Link Posted: 2/9/2011 7:33:25 AM EST
Its kind of hard to tell from the pics but I think your buffer tube is sitting alittle to far back the only thing that should stop the buffer tube is the nipple of the retainer not the body of the retainer and also i have seen a buffer tube cusion that goes on that side being damaged if you look on the web youll find it.... I think it costs 8 bucks but it saves you from replacing the buffer....
Link Posted: 2/9/2011 1:04:16 PM EST
I have seen a few ar's do that most of the time the lower is out spec abit

The hole for the detent is what out spec

the tip of detent will break off some day
Link Posted: 2/9/2011 4:31:26 PM EST
I have an old Hesse lower that does that. It has fired several thousand rounds, and shows very light marking all the way around the buffer face. I always figured the hole was in the wrong place.
Link Posted: 3/14/2011 7:46:28 AM EST
I am having the same problem with my buffer. I certainly hope it is not the lower because I went through the trouble of registering it as an SBR.

It is of reputable manufacture, but purchased on gun broker; that may have been a mistake :/

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