View Full Version : marks on buffer HELP!!
MonteSmoke
11-23-09, 23:21
A new upper on a new LMT lower. second time shooting it. when i went to clean it for the second time i noticed this. I did a google and site search but i did not know what to look for so i had no luck.
http://i6.photobucket.com/albums/y220/blkteggy/Bcgandbuffer.jpg
http://i6.photobucket.com/albums/y220/blkteggy/bcgflash.jpg
http://i6.photobucket.com/albums/y220/blkteggy/bufferupclose.jpg
totally normal. like almost all wear, its not uncommon to see what seems like drastic wear in a relatively short time.
Heavy Metal
11-23-09, 23:35
See that shiney spot on the bolt carrier just above the clearance channel for the buffer retainer? Stone it down and that wear pattern will stop.
See that shiney spot on the bolt carrier just above the clearance channel for the buffer retainer? Stone it down and that wear pattern will stop.
pff. totally showed me up.
See that shiney spot on the bolt carrier just above the clearance channel for the buffer retainer? Stone it down and that wear pattern will stop.
Yep.
I lap the rear of my carriers in a figure eight pattern using oil and an Arkansas Stone.
Take a jewelers file and some emery cloth or fine sand paper, and slightly chamfer the edge of the milled buffer detent channel in the bottom of the carrier as well.
Eliminate the burrs and you’ll eliminate the buffer damage.
http://farm3.static.flickr.com/2492/4130503500_effd6f2d92_o.png
http://farm3.static.flickr.com/2550/4129738649_8358c50392_o.png
ETA: Better pic of another carrier.
http://farm3.static.flickr.com/2544/4129756577_13cbb4cfb5_o.png
ThirdWatcher
11-24-09, 01:40
Well, you learn something new every day! The end of that bolt carrier looks really nice.
Here’s another shot of the carrier shown in that last pic above.
This is after refinishing with G96 cold blue, and about 1000 rds. Take note of the areas indicated by the arrows, and how I chamfered and rounded those sharp edges.
http://farm3.static.flickr.com/2742/4131262803_bc94f04fde_o.png
awesome pics Quib :)
Thank you Sir. :)
I just added another (current) photo above. This one shows with a bit more clarity, the areas of concern.
Yes sir. Thanks. good info to have. They'll be a bunch of us lapping our carriers tonight I imagine.
They'll be a bunch of us lapping our carriers tonight I imagine.
Hey, can you imagine a better time to be had, than lapping a bolt carrier while simultaneously lapping up a few good brews? LOL......;)
MonteSmoke
11-24-09, 15:24
Hey, can you imagine a better time to be had, than lapping a bolt carrier while simultaneously lapping up a few good brews? LOL......;)
i think i just may have to do this tonight.
thanks for the help guys.
Thank you Quib! It makes perfect sense to me, and is a nice touch. I'll be doing this from now on.
Nice bling bling on that second carrier Quib. I've never seen anyone do that before. I might have to try it on one of mine!
Joe Mamma
Yep.
I lap the rear of my carriers in a figure eight pattern using oil and an Arkansas Stone.
Take a jewelers file and some emery cloth or fine sand paper, and slightly chamfer the edge of the milled buffer detent channel in the bottom of the carrier as well.
Eliminate the burrs and you’ll eliminate the buffer damage.
http://farm3.static.flickr.com/2544/4129756577_13cbb4cfb5_o.png
Ooooo. That's puurdy.
I asked Dean Caputo about this type of wear when I took his AR operator/diagnostic course, and he said without hesitation that it was normal. If you're a perfectionist, though, it seems logical that you could flyspeck the back of the carrier and stop it.
Nice tip Quib I'm going to get the stones out tonite.
Ooooo. That's puurdy.
I asked Dean Caputo about this type of wear when I took his AR operator/diagnostic course, and he said without hesitation that it was normal. If you're a perfectionist, though, it seems logical that you could flyspeck the back of the carrier and stop it.
Normal? I’m not so sure.
Common? Yes.
Preventable? Sure is. A few minutes of lapping and I’ve prevented unnecessary wear.
Perfectionist? LOL....some say I am. I guess it goes with my profession. :)
Wear to the buffer face like that pictured above is like a number of other buffers on hand and seen elsewhere. Wear similar to this is not uncommon. I'm not sure it's "normal", but it's not uncommon.
This type of wear isn't a problem and requires no corrective action. The only wear that would be a problem would be impact marks along the edges of the buffer face in the shape of the buffer retainer pin.
Here is an H-buffer from a 6920. IIRC, this was at the 5k round mark. The wear on the buffer face progressed to this point and stopped.
http://i76.photobucket.com/albums/j18/Skintop911/IMG_2050.jpg
Wear to the buffer face like that pictured above is like a number of other buffers on hand and seen elsewhere. Wear similar to this is not uncommon. I'm not sure it's "normal", but it's not uncommon.
This type of wear isn't a problem and requires no corrective action. The only wear that would be a problem would be impact marks along the edges of the buffer face in the shape of the buffer retainer pin.
Here is an H-buffer from a 6920. IIRC, this was at the 5k round mark. The wear on the buffer face progressed to this point and stopped.
http://i76.photobucket.com/albums/j18/Skintop911/IMG_2050.jpg
I think where it could cause a problem is with cheaper metal used in the buffer. With Mil-Spec buffers it should not cause any issues.
So Quibs fix is most likely a good idea for people running cheap buffers IMHO.
C4
W
This type of wear isn't a problem and requires no corrective action. The only wear that would be a problem would be impact marks along the edges of the buffer face in the shape of the buffer retainer pin.
The wear on the outer edge of the buffer, from the retaining pin, is problematic but is caused only by an out-of-spec gun. Part of any inspection/acceptance of a gun should be a test wherein one pops open the lower and then slowly hinges it shut, watching to see that the rear of the bolt carrier pushes the buffer back slightly and off of the retaining pin.
Here is an H-buffer from a 6920. IIRC, this was at the 5k round mark. The wear on the buffer face progressed to this point and stopped.
I've got a Colt (6520 with an M4 upper receiver swapped in) with a similar round count and its buffer looks just like that. It's a non-issue from a functional standpoint and, as you say, it doesn't get any worse after a while.
I think where it could cause a problem is with cheaper metal used in the buffer. With Mil-Spec buffers it should not cause any issues.
So Quibs fix is most likely a good idea for people running cheap buffers IMHO.
C4
I have a BCM buffer in an LMT upper, and it still looks like that. I don't care how it looks, but I think it will happen to ever 'tier one' stuff or whatever it's called on the board.
thopkins22
11-25-09, 18:25
I have a BCM buffer in an LMT upper, and it still looks like that. I don't care how it looks, but I think it will happen to ever 'tier one' stuff or whatever it's called on the board.
He's not saying that it won't happen to BCM/LMT/Colt/Daniel Defense/Noveske.;) He's saying that it won't progress to the point that it causes a problem in those guns due to the higher quality metals usually involved.
I have a BCM buffer in an LMT upper, and it still looks like that. I don't care how it looks, but I think it will happen to ever 'tier one' stuff or whatever it's called on the board.
I think you misunderstand what I am saying. Yes, all buffers will show wear (even mil-spec ones).
Wear on mil-spec buffers is not going to cause a malfunction in the gun. If the buffer is made of softer metal, you could see an a problem and Quib's idea would save you from any issues.
C4
AnimalMother556
11-26-09, 15:40
I always thought this was merely a self-limiting cosmetic issue.
I always thought this was merely a self-limiting cosmetic issue.
It is. Although I don't think it odd that some people would "fix" it by smoothing out the rear of the bolt carrier.
If allowed to continue, the carrier will eventually wear directly through the hard coat of anodizing applied to the buffer. Now you’ve exposed the softer material underneath, and through continued use, I do not see the harder carrier material yielding to the softer aluminum material of the buffer assembly.
Some may consider this damage “cosmetic” and find this information useless. Once their buffer reaches a point to where they consider it unserviceable, they’ll simply replace it.
Then there are others, like myself, who do not mind taking the 20-30 minutes required to de-burr the carrier in order to eliminate any possibility of buffer damage.
If allowed to continue, the carrier will eventually wear directly through the hard coat of anodizing applied to the buffer. Now you’ve exposed the softer material underneath, and through continued use, I do not see the harder carrier material yielding to the softer aluminum material of the buffer assembly.
Some may consider this damage “cosmetic” and find this information useless. Once their buffer reaches a point to where they consider it unserviceable, they’ll simply replace it.
Then there are others, like myself, who do not mind taking the 20-30 minutes required to de-burr the carrier in order to eliminate any possibility of buffer damage.
I personally think your polishing idea is a good one. ;)
C4
I personally think your polishing idea is a good one. ;)
C4
I’ve had carriers that from the start, were machined and finished at the factory to where they basically left hardly no noticeable traces of wear on the buffer face.
Then there are those occasional carriers where I imagine the bit cutting the retainer channel was worn or reaching its life limit, and as the bit exits the carrier it leaves that slight flashing of material or burr behind.
Or, the manufacturer simply skips the finial finishing process and leaves the burrs “as is” as the carrier heads off to be parked.
Another thing I do to eliminate unnecessary wear, is at the time of lubrication I’ll apply a light film of lube to the buffer face.
____________________________________________________________________________________________________________________________________
ETA: I’m glad this topic came up. This was one of the projects I had on my line-up for a maintenance tutorial. Since this discussion started I’ve lapped another carrier, shot some photos, and am in the process of writing the text and editing.
AnimalMother556
11-27-09, 10:13
If allowed to continue, the carrier will eventually wear directly through the hard coat of anodizing applied to the buffer. Now you’ve exposed the softer material underneath, and through continued use, I do not see the harder carrier material yielding to the softer aluminum material of the buffer assembly.
Some may consider this damage “cosmetic” and find this information useless. Once their buffer reaches a point to where they consider it unserviceable, they’ll simply replace it.
Then there are others, like myself, who do not mind taking the 20-30 minutes required to de-burr the carrier in order to eliminate any possibility of buffer damage.
Never really thought of that, good point.
If allowed to continue, the carrier will eventually wear directly through the hard coat of anodizing applied to the buffer. Now you’ve exposed the softer material underneath, and through continued use, I do not see the harder carrier material yielding to the softer aluminum material of the buffer assembly.
Some may consider this damage “cosmetic” and find this information useless. Once their buffer reaches a point to where they consider it unserviceable, they’ll simply replace it.
As a practical matter, I've never heard of (much less seen) a buffer that had to be replaced because of this level of wear.
I would guess that this is because the wear is limited to only a thin layer of the buffer as eventually that "cutting surface" on the edge of the retaining pin channel no longer contacts the buffer, as the buffer is pushed off by the rest off the bolt carrier that remains in contact with a larger portion of the buffer and the "cutting edge" can no longer dig further into the buffer.
http://www.weaponevolution.com/forum/showthread.php?p=15022#post15022
I've been shooting ARs hard for about a dozen years or so and have never had any problems due to excessive buffer wear, but I only run tier one guns.
I can't really see myself lapping the ass end of a bolt carrier, but I guess if you have the time to do it then knock yourself out.
I've been shooting ARs hard for about a dozen years or so and have never had any problems due to excessive buffer wear, but I only run tier one guns.
I can't really see myself lapping the ass end of a bolt carrier, but I guess if you have the time to do it then knock yourself out.
Thanks for your input. Like I stated above, there are those who will......“find this information useless“.
Thanks for your input. Like I stated above, there are those who will......“find this information useless“.
I certainly appreciate a good caveat!! :D
It's impact marks from the buffer retainer that you need to look out for. Those will eventually cause the buffer to bind in the lower receiver extension if the retainer doesn't break first and are indicators of much larger problems with the rifle.
ThirdWatcher
12-06-09, 05:00
Hey, can you imagine a better time to be had, than lapping a bolt carrier while simultaneously lapping up a few good brews? LOL......;)
This is where I have a problem... everytime I lap up a few brews, I'm not as concerned about cosmetic damage to the inside of any of my rifles. :D
Ive been shooting my AR build and noticed weird marks around the edge of the buffer face. It looks like the pin is hitting the buffer. I took it to a local Gun Smith with a good rep for black rifles, he said the lower is probably out of spec. That would not surprise me... its a ROGGIO ARSENAL. I already ordered a better lower and a DD LPK to go in it. Is it possible I put the lower together wrong. Also any tips on the latest buffer to run on a 14.5 Middy would be appreciated.
http://i982.photobucket.com/albums/ae301/norbis1/Buffer1.jpg
http://i982.photobucket.com/albums/ae301/norbis1/buffer2.jpg
Robb Jensen
09-08-10, 20:33
Several Roggio Arsenal receivers were pretty far out of spec. They were pretty good about replacing them. I'd suggest calling/contacting them. The buffer detent hole on yours is milled too far back.
Is the rear of your bolt carrier flush with, or slightly above, the back of the upper receiver?
My guess was the hole was milled wrong or the receiver extension is screwed in too far which is pressing the buffer against the pin somehow. Just a guess.
The extension doesn't play a part in it. In normal operation the buffer only touches the detent when the upper is off of the lower. Either the detent hole is mislocated or, for several reasons, the bolt carrier is sitting too far forward. You should see, feel, and/or hear the bolt carrier push the buffer back when you pivot the upper closed.
I realize that. But, if the extension is screwed in too far then the buffer detent can't move up and down freely. If the hole isn't right then who knows.
It could also be a substandard POS buffer as well. There are plenty out there I am sure.
The extension doesn't play a part in it. In normal operation the buffer only touches the detent when the upper is off of the lower. Either the detent hole is mislocated or, for several reasons, the bolt carrier is sitting too far forward. You should see, feel, and/or hear the bolt carrier push the buffer back when you pivot the upper closed.
The detent doesn't move "up and down" during operation. The detent is purely an administrative part and the gun will run fine without it. The marks are caused by horizontal impact not vertical dragging.
The marks on the buffer are caused by it striking the detent on the battery stroke, POS or "USGI" won't change that problem.
Is the rear of your bolt carrier flush with, or slightly above, the back of the upper receiver? The BCG does sit flush with the rear of the receiver. I looked to see if it was in fact pushing the Buffer and it is not, it must be the lower then....? I wish it was the buffer! This will put a dent in my future firearms plans :( I am going with a spikes lower (the upper and BCG are spikes also, Barrel is a 14.5 DD Middy) is there any thoughts on the ST22 Buffer or one more specific to 14.5 middy buffers?
Ok, so I have two BCM uppers on RR lowers, and I am getting the impact marks on the buffer face on both rifles...I am at work at the moment and can't check, but from what I'm reading here it sounds like the upper sure isn't camming the buffer back off of the pin...soooo, is there anything short of a new lower that can be done?
I will check tonight to see if the BCG is above flush with the rear of the upper...thanks in adance for your input!!
Rob
Almost willing to bet that the detent hole is misaligned/misdrilled....
Iunderstand how the system operates. I think you are reading into what I said.
The detent doesn't move "up and down" during operation. The detent is purely an administrative part and the gun will run fine without it. The marks are caused by horizontal impact not vertical dragging.
The marks on the buffer are caused by it striking the detent on the battery stroke, POS or "USGI" won't change that problem.
Sorry for the necropost but I have been looking around for an answer and can't find it, and the OP's pictures are a good illustration of what I am inquiring about. Ignoring the marks around the edge of the buffer, what causes the straight marks/scratches on the buffer (from center outward) as can be seen in his pics?
Thanks,
Pete
Heavy Metal
10-27-11, 11:03
Burr or sharp edge at the bottom of the run-out for the Buffer Retainer clearance channel dragging on the buffer face when the weapon is broke open and closed.
Exactly. Every time you close your receiver, the tail of the carrier tensions agains the buffer face.
Ignore this and live life.
Thanks Heavy and Mark, much appreciated.
the scoring is made circular by the buffer spring slightly rotating the buffer during the recoil and battery stroke. Any high spot on the rear of the carrier will cause the circular wear in the middle of the buffer's face.
What do y'all think about these marks around the rim of the buffer? Looks to me like what some of you were referring to with respect to an out of spec lower or IG's thought about the extension being screwed in too far....
http://desmond.imageshack.us/Himg534/scaled.php?server=534&filename=sr556buffer.jpg&res=medium
Heavy Metal
10-31-11, 14:32
Looks like you have a helluva a burr on the bolt carrier. You can stone it off easily.
It's a friend's SR556, and based on the flaking finish on the detent, I was suspecting that as the culprit. I haven't seen it in person, but he swears the carrier is as smooth as a baby's bottom. Anyway, he sent that pic to Ruger, and they called him right away asking him to send it back to them for inspection.
Thanks,
Pete
as long as the rear of the carrier cams the buffer off of the detent it's fine.
as long as the rear of the carrier cams the buffer off of the detent it's fine.
If it is the detent striking the buffer during firing, would that not indicate that the carrier is not camming the buffer off the detent?
If it is the detent striking the buffer during firing, would that not indicate that the carrier is not camming the buffer off the detent?
You can look at the gun from the side when you close the receivers and watch the buffer face move rearward as the carrier pushes it off the detent.
There's no subjectivity to this. Check for yourself.
If it is the detent striking the buffer during firing, would that not indicate that the carrier is not camming the buffer off the detent?
You can look at the gun from the side when you close the receivers and watch the buffer face move rearward as the carrier pushes it off the detent.
There's no subjectivity to this. Check for yourself.
There should also be some resistance (carrier against buffer face) when closing the upper.
Check for yourself.
What he said. I can't see any impact marks along the outside edge of the buffer in your pic.
This is low normal
http://i13.photobucket.com/albums/a264/artweaker/Troubleshooting/bufferboltwear.jpg
This is fix it or end up with a bolt carrier full of buffer weights
http://i13.photobucket.com/albums/a264/artweaker/Troubleshooting/Bufferchatter1.jpg
Ouch. That bottom pic screams PROBLEM!!
Ouch. That bottom pic screams PROBLEM!!
Holy crap! The edges of the buffer look a bit like a weld seam
http://i163.photobucket.com/albums/t294/myersma2/909203a2.jpg
Ouch. That bottom pic screams PROBLEM!!
I had the same problem on a roggio arsenal lower. The buffer retainer hole is way out of spec on a lot of RA lowers. By the time I finished my build and realized what the problem was, they were no longer answering the phone. :mad:
I had the same problem on a roggio arsenal lower. The buffer retainer hole is way out of spec on a lot of RA lowers.
On a site that asks for quantification...can you quantify this? How far aft was the hole drilled? :D
Just curious on if we can establish a rough guesstimate of what measurement might be out of spec and what won't be. I have a Colt blueprint of the lower but I can't make out what the spec distance is for the hole to be drilled. Might be helpful for people that have lowers/buy lowers and get to this minutia of detail.
http://i163.photobucket.com/albums/t294/myersma2/ar15_receiver_150x150_p1.jpg
:confused:
lemme pull up my prints, I'll brb, but the first step is to make sure that the rear of the carrier is flush or slightly above the rear of the upper.
The center of the 0.255" + 0.006" diameter buffer detent hole is 0.565" +/- 0.002" from the rear of the lower receiver. Complicating things is the 6 deg pitch to the hole. Of course, that's based on the rear of the receiver being 7.503" - 0.006" from the center of the 0.251" +/- 0.001" pivot pin hole.
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