AR15 Problem
I had a major malfunction yesterday. After firing through one magazine, I inserted another & pressed the bolt catch release as normal. However, when looking to see why it would not fire, I saw that the bolt was only halfway closed. Hitting the forward assist did nothing. I tried to pivot the upper/lower receivers, but it would not allow me to. When I got home, I spent more time and by turning it upside down & shaking while holding back on the charging handle I finally heard something clattering around in there. After more shaking I was able to clear the debris and then pivot the receivers. Lying inside was the Buffer Retainer pin and spring. The pin has gouges in it from the bolt, and the spring is flattened. This would have been a major no-good in a battle situation. Can anyone tell me why this happened? It was suggested that the buffer tube was not threaded in far enough to hold the retainer pin, but it is in as tight as it will go. All help appreciated.
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Without actually seeing the rifle My first impression was the same as you mention about the buffer tube not installed correctly. Hard to tell without actually seeing the rifle. Was it a home build or factory built rifle?
IS it a collapsable or fixed stock?0 -
quote:Originally posted by Crawdog
It was suggested that the buffer tube was not threaded in far enough to hold the retainer pin, but it is in as tight as it will go.
I realize you're the one with eyeballs on this rifle, but assuming the components were manufactured anywhere near spec your receiver extension was definitely not tightened into the receiver as far as it will go. It can be threaded in to the point that the detent won't even engage the buffer.
The receiver extension is screwed into the receiver far enough to hold the detent in place, then the 'castle nut' is tightened against the receiver to lock the extension in place. Some manufacturers simply Loc-Tite the nut, but the correct method is to stake it in order to prevent exactly the issue you describe.
Sounds like either an improper assembly or a non-milspec detent that simply broke.0 -
My take: (Sorry, but I feel like being a little "wordy" today[:D]
When you close an M-16/AR type bangstick, the buffer is pushed rearward a few .000's by the bolt carrier, and is no longer in contact with the buffer retaining pin.
Thusly, the pin is only necessary to keep the buffer in place when the rifle is swung open, and is not designed to arrest the forward motion of the buffer during normal firing.
The buffer retaining pin is not a part of the firearms' operation. It's free to just "sit there" when the rifle is closed. Because of that, always screw the buffer/spring extension tube until it stops turning at the curve of the little "tit" on top of the pin..similar to forcing the pin gently forward by the extension tube. The tube must be screwed in until the pin stops it. Then, make darn sure the tube doesn't back out. Follow prior posts on how to accomplish that. Best, Joe
EDIT-info added:
Notice the little square bulge at the back end of the extension tube? It is there so you can put [5/8? not sure] crescent wrench on the tube to tighten it all the way 'till the pin stops it. Then you can back off a few degrees rotation, but not much. Best again, Joe
EDIT 2:
Craw..I just read your post below about what type of tube you have.
See if you can get an early buffer tube/stock assembly. They aren't stepped. The tube I'm talking about is (prior to threading) of a constant diameter throughout it's entire length. In theory, you can screw the tube all the way past the retaining pin hole with the tube I'm talking about. What you've done is you've reached the limit by hitting the step, when the goal here is to use the pin as the final stop-point in the threading process. Don't forget, after you've done this, back the tube off just a tiny few degrees of tube rotation. Best, Joe0 -
Thanks for the input. Replies as follows:
MVP - This is a kit gun, with full stock.
Txs & givette - The stock tube was/is threaded into the lower receiver as far as it can go. There is a shoulder on the tube that butts up against the threaded lower receiver, not allowing it to go further. At this point the tube is just touching the nipple on the buffer retainer pin - it cannot be threaded in past that point. I tested the tightness with a wrench the first thing after removing the floating pin & spring, and it was as tight as it can go.
I'll post photos if anyone thinks that might help. Again, your help with this is appreciated. I'm not real confident with the reliability of this thing.
Crawdog0 -
Are you sure this shoulder you're referring to isn't actually the 'castle nut'? It has to be backed off in order for the extension to be screwed further into the receiver. 
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That's the A1 type buffer tube. Has this rifle seen much use since the build?
Install the buffer tube and buffer detent and post a clear pic of where the detent contacts the tube.
Most likely the tube has insufficient thread length to properly retain the detent.0 -
Photos as follows. Again, all help is appreciated. [img][/img]http://www.hunt101.com/data/500/medium/ARBuffer3.JPG[img][/img]http://www.hunt101.com/data/500/medium/ARBuffer1.JPG
Also, I've had this rifle for years, with many round sent down range. Also, the Buffer Retainer Pin in these photos is a new one. The previous one was damaged (see original post).0 -
Picture is worth a thousand words. Very glad you posted them. Now, in the first photo below, notice the way the buffer is "snugged" against the retaining pin? That's where the buffer tube should be. The buffer (and the end of the tube) are supposed to rest against the little "tit" that is sticking up. You'll notice that the tube is almost flush with the receiver ring..way too far away from the pin. Correct setup should show the buffer almost flush with the buffer tube.
Conclusion: Buffer tube too far away from the retaining pin. Doesn't feel "MILSPEC" to me. Consult with a G/S as to whether a "straight cylinder" tube is OK, and go from there. With the tube you have now, you will have to shave a few .000's from the rear face of the receiver to get the tube forward where it belongs. Best, Joe
quote:Originally posted by Crawdog
Photos as follows. Again, all help is appreciated.
Also, I've had this rifle for years, with many round sent down range. Also, the Buffer Retainer Pin in these photos is a new one. The previous one was damaged (see original post).0 -
I would not shave anything off the receiver. Get a new tube or at the least turn the existing tube shoulder .050 in a lathe to get it forward enough on the buffer retainer pin that it wont come out. As was mentioned, the way the tube is currently sitting is not where it should be when tightened to the rear of the receiver.. 0 -
quote:Originally posted by MVP
I would not shave anything off the receiver. Get a new tube or at the least turn the existing tube shoulder .050 in a lathe to get it forward enough on the buffer retainer pin that it wont come out. As was mentioned, the way the tube is currently sitting is not where it should be when tightened to the rear of the receiver..
+1
It would be a simple matter to chuck the tube in a lathe and remove .05 from the face of the shoulder. Might be cheaper though to just replace the tube.
Chances are, that's a milsurp tube that got past QC. I saw 4 maybe five of them during my seven years repairing 16A1's. We would chuck them up, turn the shoulder and put them to use. Seems odd your butt stock didn't feel loose with it that far out of spec.0
![http://www.hunt101.com/data/500/medium/ARBuffer3.JPG[img][/img]http://www.hunt101.com/data/500/medium/ARBuffer1.JPG](http://www.hunt101.com/data/500/medium/ARBuffer3.JPG[img][/img]http://www.hunt101.com/data/500/medium/ARBuffer1.JPG){kind=link}
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