OK so to finish my first AR build, I removed an A2 stock from a RRA lower receiver and replaced it with a mil spec buffer tube with a magpul CTR stock on it. When I screwed the buffer tube on to cover up the buffer retainer pin, the tube would only cover a small portion of the detent spring shoulder. Unfortunately, if I gave the tube another full turn, the tube would come into contact with the nipple on the retainer pin before I could completely rotate the buffer tube. After reading about it online, some people said that I should leave the buffer tube as is and not worry about it. Others said that the retainer pin could pop up into the receiver during operation. I was wondering what you guys think I should do. here are some pics.
Ar-15 buffer retainer pin problems
- Thread starter andpinger
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courtgreene
Member
at first i thought "it's probably fine." but looking at the pictures, your description of "small" should read "miniscule." My advice is to wait for smarter people than I to come along.
rcmodel
Member in memoriam
I wouldn't like that the way it is, thats for sure.
File or belt sand off enough of the front of the buffer tube, or notch it out slightly to get another full turn and get it where it should be??
rc
File or belt sand off enough of the front of the buffer tube, or notch it out slightly to get another full turn and get it where it should be??
rc
dprice3844444
member
tube was cut too short you can replace tube or you can turn it in 1 more turn,attempt to locate where the pin is,mark it,and pull tube out and drill small hole the diameter of the tip.
Like this:
I would probably use a needle file though, and after install ensure that the bolt comes back far enough before bottoming out.
BADUNAME37
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Did you try pressing the detent pin down on your last threaded turn? It would seem that one more turn, with the pin depressed would allow for the tube to cover the pin then pop up in the notch in the buffer tube, the way it should be!
chrome_austex
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I think you're actually OK with that small amount of retention. FWIW, my rifle has about that much and is doing fine after 5000+ rounds.
If you want more (completely understandable), RC's suggestion of filing down the buffer tube to get it to turn 1 more turn sounds like a winner.
I did have to fix one RO's rifle that quit mid-match after the retaining pin decided to wander down to the trigger group area and block the hammer. He had recently installed a new buffer tube and needed an extra full turn when he put it back together.
If you want more (completely understandable), RC's suggestion of filing down the buffer tube to get it to turn 1 more turn sounds like a winner.
I did have to fix one RO's rifle that quit mid-match after the retaining pin decided to wander down to the trigger group area and block the hammer. He had recently installed a new buffer tube and needed an extra full turn when he put it back together.
Ok thank you all for the quick responses. First of all I bought the buffer tube (have no idea who the manu. was) at a gun show on a whim and in retrospect, I realize that I should have done a little research, as this tube is slightly out of spec. I did think about purchasing a new buffer tube from a more reputable manufacturer like BCM or Vltor, but that is a bit pricey... I suppose Ill probobly file the receiver extension down to accomodate the pin.
Nicky Santoro
Member
OP,
BTDT. I filed down the shoulder of the buffer tube until it went far enough in to effectively secure the pin. It didn't take much. Rifle is 100% reliable. It's possible that the lower or the tube or both are a bit out of spec. I prefer to modify the cheap part if modification is necessary to achieve function.
FWIW
YMMV
BTDT. I filed down the shoulder of the buffer tube until it went far enough in to effectively secure the pin. It didn't take much. Rifle is 100% reliable. It's possible that the lower or the tube or both are a bit out of spec. I prefer to modify the cheap part if modification is necessary to achieve function.
FWIW
YMMV
madcratebuilder
Member
You did the right fix, always mod the cheapest part. This is not to uncommon on AR's, the tube slightly out of spec, the buffer retainer hole slight out of spec, it can add up enough to create a problem.
Taurus 617 CCW
Member
The least invasive fix is to cut a relief notch on the bottom of the buffer tube. If you are confident with a dremel, you can use a fine stone to carve a rounded notch just deep enough so the tube doesn't bind on the buffer retainer. You need to be careful with a dremel because you can take off too much rather quickly. A needle file is also a viable way of removing the material. When finished, apply some Birchwood Casey aluminum black and you are finished.
The first photo shows an insufficient amount of coverage over the buffer retainer. There is a chance it will pop out at the worst time.
Here is a photo showing a relief notch I found from AR15.com
http://www.google.com/imgres?hl=en&...9&start=18&ndsp=24&ved=1t:429,r:20,s:18,i:158
The first photo shows an insufficient amount of coverage over the buffer retainer. There is a chance it will pop out at the worst time.
Here is a photo showing a relief notch I found from AR15.com
http://www.google.com/imgres?hl=en&...9&start=18&ndsp=24&ved=1t:429,r:20,s:18,i:158
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ny32182
Member
Regardless of anything else, if you have a gunshow-mystery buffer tube that exhibits one or more issues, personally I would get a milspec tube from a reputable source as a first measure to fix it. If it still doesn't look good, then maybe notch the tube.
A buffer tube is not one of the things you really want to cheap out on. Second/third the others: while that amount of retention of the pin is probably going to be functional, it is not "normal" and I'd be wondering what else might be off with the tube.
A buffer tube is not one of the things you really want to cheap out on. Second/third the others: while that amount of retention of the pin is probably going to be functional, it is not "normal" and I'd be wondering what else might be off with the tube.
ApacheCoTodd
member
You're on the right track if the other features of the receiver extension don't cause you to pitch it. Note 6 o'clock on the tube and draw a good file across it a couple-three times and you're in like Flynn.
BADUNAME37
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Good job!
Yeah, I gotta agree, you have to be careful at gun shows!
You can end up with literally anything -- and, most likely at a price that would have permitted you to buy an OEM Tube with a manufacturer name attached so you know what you are getting is mil-spec.
Yeah, I gotta agree, you have to be careful at gun shows!
You can end up with literally anything -- and, most likely at a price that would have permitted you to buy an OEM Tube with a manufacturer name attached so you know what you are getting is mil-spec.
adelbridge
Member
if the detente pops out during a live fire cycle your lower receiver will be destroyed. If you bought this gun to possibly defend your life I would recommend a tube that fits properly.
Ok so at this point I agree with NY and Friendly... Before I tightened the castle nut on the receiver extension, there was a good amount of play between the lower and buffer tube when I had it screwed into its current position(not sure if this is normal). As I have already spent 4 figures on the firearm and planned on being able to use it in a defensive situation, I suppose it would be the best plan to go ahead and purchase a new buffer tube from a reliable manufacturer.
As a side not, the standard carbine buffer and buffer spring that I have were also purchased from a rando at the same gun show... should I buy from a more reliable source or should I be G2G with those parts??? When I have those parts installed, there seems to be a lot of "springy noise" when I tap the buffer tube... I feel like they could be too loose, but at the same time I have a feeling this could be normal for a carbine stock.
As a side not, the standard carbine buffer and buffer spring that I have were also purchased from a rando at the same gun show... should I buy from a more reliable source or should I be G2G with those parts??? When I have those parts installed, there seems to be a lot of "springy noise" when I tap the buffer tube... I feel like they could be too loose, but at the same time I have a feeling this could be normal for a carbine stock.
Like this:
I would probably use a needle file though, and after install ensure that the bolt comes back far enough before bottoming out.
68WJ, what exactly do you mean by "ensure the bolt comes back far enough before bottoming out" Thanks.
You are screwing in the tube further than it was designed. There is a slight chance that there won't be enough room for the carrier/buffer to come back far enough to lock back under normal operation. It shouldn't be a problem, but neither should installing a buffer tube.
NEVER twist the buffer tube too far in or you will jack up the detent.. I had to replace the spring and detent on my AR... you want to screw the buffer tube in just enough for the detent to catch and not pop out but not too much or the detent won't freely go up and down on the spring... I just recently went thru all of this with AR I just built. good luck.
Cool thank you all so much for your helpful replies!.. Do any of you have any idea of whether I should stick to the buffer and buffer spring which I got from a gun show... they seem to be perfectly fine.... but so did my buffer tube
Unless there is an obvious defect, there is no way to know until you shoot it.
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