View Full Version : Something sliding back and forth in the buffer tube?
I've got a question about an new to me, DPMS, 6.8mm model #M-150. I noticed that the FSB is canted a little to the left. I'm going to try and remedy the problem but have to wait until I can get a fixture with which to hold the receiver in a vise. Until then, I've got the upper and lower separated. I've noticed that when I raise and lower the forward end of the lower assembly, with the stock removed, I can hear and feel something sliding in the buffer tube. Is that a normal sound? I had originally thought that the rattling that I was hearing was coming from the stock only. There is spring tension when I push on the end of the buffer.
This is my first AR type rifle. Please excuse my ignorance of the subject. Tried a search but didn't really find the answer that I was looking for.
Thanks for any help, crispy
Have you taken the buffer out to see if there's any debris in there that might be causing the sound in question?
Dionysusigma
01-17-11, 14:39
Probably the weights inside the buffer moving around a tiny bit. It's normal--in fact, it's intended. Nothing to worry about. :)
On the lower receiver, there's a pin that holds the buffer and spring assembly in place. Push that pin down and the buffer will go forward and you can pull it out and inspect/clean/wipedown. For assembly, just put the buffer on the spring and push it back into the receiver extension.
http://i103.photobucket.com/albums/m127/johnson_n/IMG_1268.jpg
Have you taken the buffer out to see if there's any debris in there that might be causing the sound in question?
Hi Steve
No, I haven't removed the buffer tube yet. If I found out that the sound was normal I was just going to leave it be. If not normal, I wanted to wait until I got the fixture block. Kind of want to preserve the "like new" condition of the rifle. (I'm little anal when it comes to stuff like that)....lol! What I'm hearing, sounds bigger than just debris though.
Thanks, crispy
On the lower receiver, there's a pin that holds the buffer and spring assembly in place. Push that pin down and the buffer will go forward and you can pull it out and inspect/clean/wipedown. For assembly, just put the buffer on the spring and push it back into the receiver extension.
http://i103.photobucket.com/albums/m127/johnson_n/IMG_1268.jpg
Great! I didn't know that the pin could be depressed. Thanks guys.
Probably the weights inside the buffer moving around a tiny bit. It's normal--in fact, it's intended. Nothing to worry about. :)
I was afraid that someone would say that. It's going to drive me nuts. How do sneak up on something with a rattly gun? lol!
crispy
If that DPMS didn't come with a manual of some sorts I suggust that you get over to Amazon.com and order the following,
Army Technical Manual (for M16 rifle) - TM9-1005-249-23P
Army User's Manual (for M16 rifle) - TM9-1005-249-10
USMC Basic Marksmanship Manual
If that DPMS didn't come with a manual of some sorts I suggust that you get over to Amazon.com and order the following,
Army Technical Manual (for M16 rifle) - TM9-1005-249-23P
Army User's Manual (for M16 rifle) - TM9-1005-249-10
USMC Basic Marksmanship Manual
Thanks.....I will.
Probably the weights inside the buffer moving around a tiny bit. It's normal--in fact, it's intended. Nothing to worry about. :)
It is the weights inside of the buffer. Thanks
Hi Steve
No, I haven't removed the buffer tube yet. If I found out that the sound was normal I was just going to leave it be. If not normal, I wanted to wait until I got the fixture block. Kind of want to preserve the "like new" condition of the rifle. (I'm little anal when it comes to stuff like that)....lol! What I'm hearing, sounds bigger than just debris though.
Thanks, crispy
I didn't mean to remove the entire receiver extension (buffer tube). I just meant to remove the buffer itself as Johnson described.
I didn't mean to remove the entire receiver extension (buffer tube). I just meant to remove the buffer itself as Johnson described.Yeah, when you told me, I didn't know that the retaining pin could be depressed. I thought that the only way to get the buffer and spring out, was to remove the extension. My bad. Now I know better. Thanks again everyone.
crispy
lethal dose
01-17-11, 16:16
Dude. I'd get on the horn with dpms. The fsb cant is wrong and THEY need to make it right.
Dude. I'd get on the horn with dpms. The fsb can't is wrong and THEY need to make it right.I agree but I didn't buy the rifle new. I traded for it with a guy from out of state.
I could have not went through with the trade but instead decided that I'd rather not have to deal with the waiting, extra expense and hassles. I figure I'll just fix it myself.
Crispy
thopkins22
01-17-11, 19:10
I've got a question about an new to me, DPMS, 6.8mm model #M-150. I noticed that the FSB is canted a little to the left. I'm going to try and remedy the problem but have to wait until I can get a fixture with which to hold the receiver in a vise.
Don't do that...the front sight base is pinned, meaning it's not going to just turn with force.
The only thing you'll wind up accomplishing is destroying your upper or putting too much bend in your gas tube, as there is also a bit of metal on the barrel that indexes into a cut on the upper receiver to hold it straight.
If it zeroes okay, I'd drive on and forget about it, if it doesn't then I'd send it back to DPMS.
Don't do that...the front sight base is pinned, meaning it's not going to just turn with force.
The only thing you'll wind up accomplishing is destroying your upper or putting too much bend in your gas tube, as there is also a bit of metal on the barrel that indexes into a cut on the upper receiver to hold it straight.
If it zeroes okay, I'd drive on and forget about it, if it doesn't then I'd send it back to DPMS.Thopkins, no worries about my bending or trying to force anything. I am planning to either remove a slight amount of stock from the key that indexes into the notch in the receiver or remove a little stock from the left side of the notch in the receiver and then staking the opposite side to take up any extra space. If I find out that the problem is the FSB being mounted wrong on the barrel, I will call DPMS about it. If I thought DPMS would do anything about this, I would send it to them. I'll try and give them a call tomorrow and see what they say.
My only other plans for this particular rifle are to upgrade the bolt and carrier assembly and torquing to spec. and staking the castle nut that is holding the receiver extension tube onto the receiver. Maybe a new trigger guard and trigger assembly.
Thanks for your concern, Bill
Thopkins, no worries about my bending or trying to force anything. I am planning to either remove a slight amount of stock from the key that indexes into the notch in the receiver or remove a little stock from the left side of the notch in the receiver and then staking the opposite side to take up any extra space. If I find out that the problem is the FSB being mounted wrong on the barrel, I will call DPMS about it. If I thought DPMS would do anything about this, I would send it to them. I'll try and give them a call tomorrow and see what they say.
....
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I could be wrong but if you move the barrel by giving more room in the notch, wouldn't the relationship between the barrel extension and the bolt be out of alignment?
Just wondering...
.
The_Hunter
01-17-11, 22:32
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I could be wrong but if you move the barrel by giving more room in the notch, wouldn't the relationship between the barrel extension and the bolt be out of alignment?
Just wondering...
.
you are correct
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I could be wrong but if you move the barrel by giving more room in the notch, wouldn't the relationship between the barrel extension and the bolt be out of alignment?
Just wondering...
.
You have brought up a valid point. I really can't answer you because I haven't been able to remove the barrel to see what I'm going to be dealing with. I will however keep what you said in mind.
Thanks, Bill
you are correct
Well, with that being said, I might just see if I can sight it in like it is. Just bothers the heck out of me looking at a canted sight. Maybe I can hide it from view with a scope or something.
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I could be wrong but if you move the barrel by giving more room in the notch, wouldn't the relationship between the barrel extension and the bolt be out of alignment?
Just wondering...
.
On another note. If the FSB is mounted correctly, wouldn't the problem that you mention, already exist?
... Maybe I can hide it from view with a scope or something.
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Knowing DPMS, if you're lucky, it'll be canted enough to not even be in the FOV of your scope ...
Then, just shim your rear sight so it leans to that same side...what else you need?....! ;)
.
The FSB being canted could simply be a result of the FSB being drilled improperly.
On another note. If the FSB is mounted correctly, wouldn't the problem that you mention, already exist?
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Knowing DPMS, if you're lucky, it'll be canted enough to not even be in the FOV of your scope ...
Then, just shim your rear sight so it leans to that same side...what else you need?....! ;)
.
It's not that bad....lol!
The FSB being canted could simply be a result of the FSB being drilled improperly.
I hope to find out as soon as I can get the barrel off. Just want to wait until I can do it right.
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