AR 15 buffer damage... anybody seen this before?

Reason - the upper is out of spec. Mostly likely, the barrel extension is too long and the barrel sits too far, when the breech is closed the BGC is too far forwards.

Look at your upper in the picture - the bolt carrier is flush with the upper at the open end. That is not right.
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I'd have to disagree.....the buffer should sit just ahead of the 'tower'. If you look at it from the side, you should be able to see the buffer sticking out of the tube a bit. Then when you close the upper on the lower, the carrier, which should be flush at the back of the upper pushes the buffer backwards (preloading it if you will) so that it (buffer) is no longer resting against the pin. If the carrier sticks out past the end of the upper, you wouldn't be able to close it, it would hit the top of the 'tower'.

Added: If the OP's pin conversion kit IS sitting the upper too far forward of the 'tower', it would also have the same effect. However, I can't comment without seeing them (upper and lower) together.

I still think that the buffer reatiner is in the wrong spot (too far to the rear). And you can't measure the distance to the reatiner from the back of the receiver because (if you look at the actual drawings for a lower) the size is taken from the selector hole. What this means is that the back of the lower receiver could be longer or shorter than spec but as long as the retainer hole is drilled to spec with the takedown and selector holes, the buffer will be in the correct position.
 
i've been running a large hole upper colt with adapter on a regular armalite-eagle small hole lower, with no problems or damage like that seen in the pictures.

that lower definetly looks to be out of spec at the tower-retainer, so what would be a course of action for the fellow?.
 
well, it depnds how far out it is. It's possible that MAYBE, if you turned down the diameter of the retainer where it holds the buffer back (not the large diameter underneath the tube) it would allow the buffer to move forward more BUT it could also weaken that small pin to the point where it COULD break.
The EASIEST way to 'fix' the problem, is to remove the retainer totally. The downside is you have to hold the buffer from flying away when you open it, and kind of push it back out of the way when you close it. I know someone who has a carbon15 lower that has no retainer (or hole for a retainer) and that's what he does (and it suits him just fine), and really, it's not a HUGE deal, BUT some people may not want to go that direction.

A more difficult method would be to fill in that hole and then re-drill the hole in the correct position. To fill it in you could either fill it with weld (which IMHO would be a huge PITA), or you could pack it full of J-B Weld. Then you would re tap the buffer tube threads, then you would set it up and re drill the hole (it's on a 6 degree angle). I wouldn't advise doing this with a hand drill or a drill press. A milling machine is the proper way to go.
 
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backing off the buffer tube isnt going to help if the pin is in the wrong spot. the buffer will still come forward until it hits the pin regardless of where you have the buffer tube screwed to.
 
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Your buffer hitting the buffer retainer with each shot is not the major cause of damage. That does happen, and it does damage the buffer face, but it has two defining characteristics:
- the perimeter of the buffer face is scored by hundreds of short, radial lines, all of about the same depth. You can see a little bit of this on the upper left in your photo.
- the buffer retainer has a short life, typically breaking within a couple of hundred rounds.

Your buffer has suffered a whole bunch of damage on a handful of occasions, as opposed to a little bit of damage every time it was fired. Whatever it is, is happening once per range session, once per cleaning session or something like that.

ETA: Found a pic, courtesy of Dano523 over at AR15.com. See the perimeter damage indicated by #1:
bufferfacemarkedup.gif
 
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You guys are a wealth of information...

Greentips : I checked the carrier and it flush with the back of the upper..

With regards to rotating the eccentric spacer in the front hole.. if i move it at all in any direction, the take down pin is not aligned with the hole and it wont go thru.. so rotating the spacer is not an option..

If i rotate the buffer so that the pin is resting on fresh metal, i can see daylight thru the space where the lower and upper meet.. If i rotate the buffer so that the pin is sitting in one of the "dings", i don't see daylight, which leads me to believe that the carrier is making contact with the buffer..

it seems that its not off by much..

i dont have access to a milling machine to drill a new hole, nor would i trust myself with one..

Like MALICE said. its not a huge issue to even take the pin out for me..

I like Y2K's idea of sticking a quarter on the buffer with some epoxy.. that seems like the simplest solution..

It really isnt a big deal for me.. as long as it shoots well (which it does) I dont have a problem with a fix like that..

regarding the other questions and comments-

-the barrel is marked 5.56 NATO, and i've shot both .223 and 5.56 thru it.

-the sling adapter is on the list

-i dont think this "dinging the buffer thing" is exactly "beating the hell out of my rifle"

thanks guys, i'll keep you posted
 
don't add a quarter to the buffer. the quarter is not flat. the coin will have to wear smooth, with all the metal bits flying around the gun. plus i don't think hard metal again the bolt carrier is a good idea. there is a reason why the buffer is made of aluminum.

the pin hole is drilled too far back. you can't fix it. unless you weld up the hole, rethread it and then drill a new hole.

just run it without the buffer pin. makes opening it a pain, but there will be no more damage.
 
Just throw a quarter in and replace each time it`s been to the range. don`t bother to glue it just replace it everytime. I have similar problem with a Norinco, and just pass the quarter off at some store. Cheap fix.

I`ve been doing it for about 7 years now with a round count of 7000+ and no problems.
 
P0WERWAGON said:
don't add a quarter to the buffer. the quarter is not flat. the coin will have to wear smooth, with all the metal bits flying around the gun. plus i don't think hard metal again the bolt carrier is a good idea. there is a reason why the buffer is made of aluminum.

the pin hole is drilled too far back. you can't fix it. unless you weld up the hole, rethread it and then drill a new hole.

just run it without the buffer pin. makes opening it a pain, but there will be no more damage.
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i thought about the quarter thing being too hard (metal on metal)..

i just glued a piece of hard plastic onto the buffer ... its almost the same width of the retainer pin and it seems to be working.. i left a small cutout on the part that goes up against the pin so that the plastic piece sits out just past the pin...

when i close the the upper and lower, i can see the buffer being pushed back into the spring..

i slammed the bolt a bunch of times and no new marks so far.. i''ll range test it on the weekend and see what happens..

worst case scenario, i'll take out the pin like you said.
 
Why not just relief the face of the buffer a little until the necessary clearance for the retainer pin is obtained? Not the whole face of the buffer, but rather the part (ring) where the retainer pin contacts the buffer. Then the center of the buffer will be further forward and contact the rear of the carrier as it should, but the edge of the buffer's face will be a bit further back and won't be able to contact the pin. I know, it would have to be machined to make it precise, but it shouldn't be too hard, nor too expensive to do. Heck, with a buffer so battered, I'd dare to do it even with a Dremmel tool. What do you guys think?
 
Gun Lover said:
Why not just relief the face of the buffer a little until the necessary clearance for the retainer pin is obtained? Not the whole face of the buffer, but rather the part (ring) where the retainer pin contacts the buffer. Then the center of the buffer will be further forward and contact the rear of the carrier as it should, but the edge of the buffer's face will be a bit further back and won't be able to contact the pin. I know, it would have to be machined to make it precise, but it shouldn't be too hard, nor too expensive to do. Heck, with a buffer so battered, I'd dare to do it even with a Dremmel tool. What do you guys think?
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What you are saying will not work. There is a spring behind that buffer so you could take 5mm of of it and the spring will just push it forward more.
 
glock9x19 said:
What you are saying will not work. There is a spring behind that buffer so you could take 5mm of of it and the spring will just push it forward more.
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Got it! But I was thinking more like 2 mm, not 5 mm. Anyways, I'd try it if it was me, but I'd still keep looking for a more permanent solution.
 
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