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Posted: 3/28/2006 11:05:10 AM EDT
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Homebuilt AR, fired it for the first time and I took it apart to clean it and my buffer is all chewed up from the retaining pin??? DId i put it together wrong, why is it taking a beating like this? Maybe did I install the tele stock too far forward making the buffer hit the pin everyround?? or is this normal? |
This is where my money would be at. Long scratches across the face can be made by the burr contacting the buffer face when you open/close the receivers together during takedown. A round circular wear pattern is from the buffer rotating during recoil and the burr mashing into the buffer face with every contact. Seen it lots, can't believe such a minor thing can make such a major looking mark. Let us know if that's not it... Sly |
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I'm about 3/4 convinced that at least part of the problem is the finish put onto aftermarket, as opposed to Colt, buffers. Yes, they look the same, but the fact is that the Colt buffer on my 1977 made SP1 carbine, w/thousands of rounds on it, shows less finish wear than the DPMS piece I have w/only a few hundred rounds thru it. Also, the fairly new Colt rifle buffer I got w/the M16A1 stock set from CDNN awhile back, while it has only a few hundred rounds, is showing essentially zero wear at this point. Yes, it's certainly true that a burr, or a retainer hole that's too far forward by a few thousanths, can cause this type of front face marking, but I remain to be shown that at least part of the problem isn't in a less drable finish.  |
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Not likley. The buffer isn't going to come forward that far. If it did, the retaining pin would get broken. The only thing the pin does for you is hold the buffer in place during assembly of the rifle. If you took it out completely, you could still shoot the rifle just fine. I've got about 15 rifles that have the same problem. Trust me. It's completely around the buffer because of the buffer spinning during the cycle of operation. Are there any machining marks on the back of the carrier or does it APPEAR smooth? |
| I had the same thing happen to my build. The CMT carrier had a burr right where the slot is cut in it to slide over the buffer retaining pin. It left short marks in the face of the buffer all the way around it. I took some emmery cloth to and smoothed it out. I dint think it would hurt anything but I figured I'd get rid of the burr just in case. |
I posed that question once and got nearly the same replies
Photo of the one I was referring to 
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Mine doesn't look like that... maybe i can post a pic. how can i tell if Installed my buffer tube on my m4 stock too far forward? |
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With the front pin in, and the bolt in battery, as you hinge the rear down, to slide the takedown pin, the buffer should get slightly pushed back as the bolt carrier comes in contact with it. It should NOT stop on the retaining pin. It's there to keep the buffer in place when taken apart. It shouldn't matter how far the tube is screwed in, as long as it capitvates the retaining pin properly. |
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1911greg.......... there are 2 distinctive sources of your damage. The inner ring of damage is from the carrier slamming rearward into the buffer. Not good. This a result of either an improper buffer installed (too long) or carrier imperfections. This can be checked by physical inspection and feel of the rear surface of the carrier. The problem should be obvious the outer ring of the buffer damage is clearly the buffer retainer pin. Based on the presence of both impact markings, I believe your problem to be either the buffer, carrier travel, or retainer detent pin If you have "others" use them. That issue could result in worse problems than a damaged buffer |
| looks like you both have carbine stocks and i'll bet that they aren't carbine buffers though. either that or you bought your BCG groups in pieces and the spacing and whatnot is screwy in those. Also make sure you are using the right spring and not some hardware store knockoff which could be 10x too strong |
did it happen right when you got the rifle mine only has 200 rds through it. |
thx but wouldn't backing the pin out cause the pin to actually rise up a little? |
Based on the pictures I would say the buffer retaining pin hole was drilled too far to the rear. The result is that instead of the buffer resting against the bolt carrier when closed it is resting against the pin. Unfortunately if this is the case there is nothing that can be done besides removing the retaining pin and running it without. If it were me I would contact the manufacturer and let them know. |
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You have 2 problems here: The back bottom of the carrier is sharp. File the sharp edge. The buffer is smacking the pin. Sooner or later the pin is going to break, and the pieces and spring will fall into your FCG. Is the carrier when in battery contacting and pushing the buffer off the retaining pin, when hinging the rear closed? |
This is what I want to know! If there is a gap between the carrier and the buffer, the carrier will have time to gain a good amount of velocityt before it SMACKS the buffer, and could be the source of the inner ring marking. As the buffer/carrier returns to battery the buffer will SMACK into the retaining pin, and could leave the outer marks. Tex78 |
That buffer and stock had about 1500 rnds on it before I built the varmint upper for it. When I did that I got a new upper(CMT),barrel(bushmaster),and new complete bolt carrier and bolt(CMT). After I fired the first round to break in my barrel I broke the rifle down to clean the barrel and noticed 1 mark was on the buffer. I thought about it and remembered that there were no marks before that but didnt think much of it. Then after my second shot I did the same thing and there was another mark, then I started inspecting and noticed a very small burr(just barely enough to catch my finger nail) on the bottom back of the carrier where it is grooved to slide over the buffer retainer. I didnt have anything to file it down with at the time and I wanted to get my new barrel broke in so I continued shooting(this is why there are so many marks on it in the pic). After I got back home from the farm I filed the burr off and havent had any new marks on the buffer. So to make a long story short, yes it happened with a brand new carrier. |
Yeah , DUH  , can't believe I typed that .Been workin too hard  My First post I said to back the tube OUT - Then I saw his pin was a little high , so I edited that in. Second post I Meant to say screw the tube in - which would lower the retaining pin a bit. Anybody know a cure for Alzheimers? 
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