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AR-15 Recoil Buffer Damage Question

14K views 16 replies 6 participants last post by  smokemup 
#1 ·
I use my AR-15 lower for both my 223 varmint upper and my Tactical Solutions 22LR conversion unit upper.

Recently it has been mostly in the 22LR configuration. When I just cleaned it I noticed that the front of the buffer tube shows signs that the stop pin in the bottom of the cavity is beating up the outside edge of the buffer face. The vertical face of the buffer tube has chatter marks on its edge all the way around. Is this at all normal?

Was it the 223 that did this damage of the 22LR conversion unit? It seems very unlikely it could be the 22LR conversion unit as it uses its own recoil system and the one in the stock only backups the conversion unit in recoil. The gun regularly gets 22LR Std Vel ammo which it likes. I don't remember using Hi Vel but it is possible (??). Could it be that the conversion unit actually pushing the buffer tube to the rear and the buffer easily over powers the closing of the conversion unit and slams into the stop pin?

I had not noticed this damage in the past but I really was not looking for it. I have no idea whether the 223 or 22LR caused it.

Anyone got any ideas?

LDBennett

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#2 ·
I have never seen anything like that. I was curious so I just went and checked out the buffer in my ARs. None of them have any kind of damage on them like what you show. I check three .223s, one 7.62x39, and the dedicated .22 long rifle upper. I don't really see how the .22 bolt could cause that damage, but mine is a dedicated upper and not a drop in unit. The drop in has that long spring what (I guess) could cause the rear of the unit to slam into the buffer.

Is there any damage to that pin that holds the buffer in?
 
#3 · (Edited)
My son's AR in 223 is as yours with an un-molested buffer.

It is a complete Tactical Solutions upper. It slides in and rests against the buffer to absorb the recoil. The very top of it rest against the top of the buffer tube receptacle on the lower. There are tiny marks on both the drop in "bolt assembly" and the front of the buffer tube receptacle where the two have been touching during firing. So the Conversion Unit does not use the buffer recoil spring at all and is held in place.

Look at this picture.
Silver Metal Glass Silver Aluminium


This is the back of the Conversion Unit. At the top is the guide rod for the Units recoil spring (Note the cutout at the bottom for the pin that retains the buffer tube in the lower). When the gun is fired the bolt moves to the rear against the Unit's recoil spring. The spring, as it collapses, drags on the guide rod and the guide rod is kicked back against the edge of the buffer and marks it (the buffer is aluminum and easy to mark). So I see the mechanism (the guide rod lines up perfectly with the damage to the buffer), and when I move the bolt back I can feel and see the rod dragged to the rear by the units recoil spring collapsing. It definitely is the Conversion Unit doing the damage.

How to fix it? I just bought from Brownells a plastic buffer for the face of the buffer. That should protect the buffer face. They probably will die easily with gun use so I bought several. Then I'll look to see if the clearance between the guide rod and the spring can be loosened so they slide on each other smoothly. This may not be possible. or find a way to capture the end of the guide rod so it can not move to the rear (??).

Thank you gdmoody for the input.

LDBennett
 
#4 ·
Talked with TacSol today and the rep. said he had never heard of this before. I sent pictures and they are pondering them. We'll see what they say.

While my explanation seems plausible, the damage to the buffer goes farther towards the center than the Units recoil spring guide rod seems to be able to reach. Maybe with tolerance of the gun and looseness of the Conversion Unit in the upper the rod could reach (??). I await TacSol's response. Meantime I have ordered a better recoil spring for the lower that is suppose to take out the twang and may stop any oscillation of the spring and buffer. While this is not a solution to the 22LR problem it can help 223 operation. I also have ordered some recoil buffers for the front of the lower's buffer or the back of the Conversion Unit to confine the Conversion Units recoil spring guide rod's rearward movement.

I'll say up front that this is a confusing problem. While I think I have found the buffer damage mechanism, part of the evidence does not totally support my theory (???). We'll see what TacSol says.

LDBennett
 
#6 ·
I got no feed back from TacSol. I don't really know why this happened but I am leaning towards that it was not the TacSol 22 upper. The lower has been used with my 223 upper for several years. I never noticed the damage before several trips to the range with the TacSol upper installed but I was not really looking that close for this kind of damage to the buffer. So here is what I think is happening:

I think that when used as a 223 that the stock recoil spring surges back and forth with every firing. It starts surging after the bolt and bolt carrier are in battery. You can hear it happening as the gun is fired as the noise inside the stock after the gun has fired. With the bolt closed the buffer is free to move with the surging spring and stop against the steel pin in the bottom of the buffer tube. The surging must make the buffer rotate making the damage seen in the picture. The marks on the buffer correspond to the stop pin in the buffer tube.

I saw a informational video from Damage Industries where they say their recoil spring made of a different material (stock is a stainless steel alloy) does not surge. So I put one in the buffer tube but have yet to test it. I also installed a thin plastic buffer from Brownells on the face of the buffer. That plastic buffer will take the abuse rather than the aluminum buffer. The plastic buffer appears to be a piece of 1.7mm ( about 0.070 inches) clear acrylic with adhesive on the back. I have no idea how durable it is but I bought spares just in case.

What is perplexing to me is the other 223 AR I have does not do this but you can hear the recoil spring surging inside the stock too. But it is new and has maybe 200 rounds through it so that may be why its buffer tube is not damaged yet (??).

So I'll have to make a range trip to see if any of this fixed the gun(??).

LDBennett
 
#9 ·
I also inspected my S&W M&P 10 (308 AR-10) which uses a similar design and it has no signs of damage to the buffer. It too is pretty new with maybe 500 rounds through it. I did stick plastic buffers on both 223 lowers and on the 308 lower. I too hope this gets it.

LDBennett
 
#10 ·
There were a couple response on another web page where I posted this and they saw similar damage. They each added the plastic buffer and the problem of damage to the buffer of course went away as its end is now protected.

This is all very weird. All I can think of is the surging of the recoil spring but they all do that????? Supposedly I stopped that with the addition of the non-surging Damage Industries Chrome Silicon Steel (??) recoil spring vs the Stainless Steel Mil-Spec recoil spring. Testing is pending.

The bare lower is a Double Star bought several years ago with Mil-Spec internals bought from Brownells. The uppers are the Tac Sol complete 22LR upper and the American Spirit (now out of business) 223 complete upper with all their parts. The fit of everything is perfect. American Spirit went out of business due to family conflicts, not do to inferior products, as best I know.

LDBennett
 
#12 ·
OK...Tested things today.

The Buffer spring was replaced by the Damage Industries spring that is suppose to minimize surging of the spring. Placed the plastic buffer that appears to be a piece of 1.7mm ( about 0.070 inches) clear acrylic on the buffer which would easily show any pounding of the edge that the buffer might be getting.

I shot 100 rounds of 22LR both Std Vel and High Vel in the TacSol 22LR complete upper (does not use the buffer spring as it has its own recoil spring). Inspected the buffer after shooting and absolutely no damage to the buffer face that is covered by the clear acrylic added buffer.

I then shot 40 rounds of 223's (full loads behind Hornady 75 gr HPBT Match). Again inspected clear acrylic buffer added to the real buffer face. There was absolutely no damage to it.

Whatever caused this problem in the first place appears to be gone. There was a gunsmith/AR competitor at the range and I discussed it with him. He had never seen this kind of damage to a buffer but was convinced if either of the uppers caused it then it probably was the 223 upper. He suggested that it may be the bolt carrier is not being force hard enough against the buffer but in inspecting it he saw no problem there.

So the problem is gone and the gun will stay in this configuration forever. I'm happy at the outcome but upset I did not really find the culprit for the damage. Oh well, nothing in life is totally conclusive except death and taxes.

LDBennett
 
#14 ·
I had one do that, the hole for the buffer retainer was incorrectly positioned too close to the rear of the lower and the buffer was riding on it instead of against the bolt face when the bolt was closed, so when fired, the bolt would slam into it rather than it just ride back into the stock tube as it should. Sent the lower in and they replaced it, new one runs just fine.
 
#15 ·
I've been following this thread and checked all my ARs and none of them show any sign of damage like that. The only thing I could think of was the material on the buffer face was softer that the buffer retainer pin. That might cause the chatter you see around the edges.
 
#16 ·
stev32k:

Yes, the retaining pin is steel and the buffer is aluminum. But the clear acrylic add-on buffer face is softer yet and it now shows no marks at all from the steel retaining pin. It is a mystery that may never be solved, at least by me because the gun now works fine without damaging the buffer.

LDBennett
 
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