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4/23/2010 7:47:58 PM EDT
I installed a milspec buffer tube on a new lower and slid my CTR stock onto it. When it's in the shortest position, it seems like it sticks and I need to rotate/wiggle the stock to get it to move back to other positions. This doesn't happen on another lower I have.

Anyone know how I could fix it, or modify the tube to stop "grabbing" the stock?
4/23/2010 8:09:21 PM EDT
[#1]
Is the release lever working?
4/23/2010 8:28:28 PM EDT
[#2]
Since the stock works in other positions, it sounds like the difference must be in that portion of your buffer tube.  The CTR might be tighter than a regular buttstock, but putting on a regular stock and checking for problems would be a possible way to troubleshoot.

 I'd check the first two inches of buffer tube for burrs or irregularities.
4/24/2010 4:32:09 AM EDT
[#3]
I've had 2 milspec CTR stocks do this very same thing in the most closed postion. I have not diagnosed the problem, but it's not that big of a deal to me. Tag for other responses...
4/24/2010 4:35:20 AM EDT
[#4]
Quoted:
I've had 2 milspec CTR stocks do this very same thing in the most closed postion.


+1

I likewise have 2 milspec CTR stocks and they do the same thing in the shortest position. This happens on a DSA and BCM buffer tube.
4/24/2010 5:39:52 AM EDT
[#5]
I have 2 CTR stocks on mil spec tubes that don't do this at all, they slide free in all positions.  My son bought a CTR a couple of weeks ago that was commercial spec. for his gun that is mil spec by mistake.  It did the same thing that you describe above, he has not had a chance to try the proper stock yet.  I found this to be very strange though because the commercial tube is bigger than the the mil spec, and you would think it would have had excessive play if anything.
4/24/2010 6:19:34 AM EDT
[#6]
The release button works fine, it's the actual sliding of the stock that sticks in the most closed position. I know I'm using all milspec. I ordered an ACS to go on this rifle anyway, so I'll see if that has the same problem, I just threw the CTR on for kicks when I finished the lower.

It sounds like it's not a unique problem only to me.

Thanks...
4/24/2010 6:56:17 AM EDT
[#7]
I have a spikes milspec tube and a ctr. Mine also sticks in the fully collapsed position. I think the opening on the stock binds on the exposed threads on the buffer tube by the castle nut. Mine only gets stuck if i collapse it kind of hard. If I close it real slow it does not stick, that's why I think it sticking on the threads. I have been meaning to get a file after the the end of the opening of the stock to smooth it out just have not had time.

James
4/24/2010 7:06:26 AM EDT
[#8]
The stock is probably getting caught on the threads of the receiver extension.
I had the same issue and lightly beveled the inside leading edge of the stock with a round file and fixed the problem.

Took all of two minutes.
4/24/2010 7:22:21 AM EDT
[#9]
Quoted:
I have a spikes milspec tube and a ctr. Mine also sticks in the fully collapsed position. I think the opening on the stock binds on the exposed threads on the buffer tube by the castle nut. Mine only gets stuck if i collapse it kind of hard. If I close it real slow it does not stick, that's why I think it sticking on the threads. I have been meaning to get a file after the the end of the opening of the stock to smooth it out just have not had time.

James


This.  My situation exactly.  Doesn't bother me though.
4/24/2010 7:39:22 AM EDT
[#10]
Quoted:
The stock is probably getting caught on the threads of the receiver extension.


I think we may have found the issue!
4/24/2010 6:42:45 PM EDT
[#11]
I would agree with the sticking on the threads, that's where it seems to be a problem.

I'll try to file the plastic and see if it works.
4/24/2010 7:29:54 PM EDT
[#12]
Could someone tell me the difference between the Mil spec and commercial version of the CTR Stock
4/24/2010 7:54:45 PM EDT
[#13]
Quoted:
The stock is probably getting caught on the threads of the receiver extension.
I had the same issue and lightly beveled the inside leading edge of the stock with a round file and fixed the problem.

Took all of two minutes.


This is the correct answer.  On a mil-spec tube, the threads are thicker than the tube.  The stock is sized to fit the smaller diameter tube.  The solution is to take a file - preferably a rounded file such as for wood working, and bevel in the inside edge of the CTR.  It'll take a few minutes, but not difficult.  

I'm a little disappointed Magpul doesn't do this already, as this is a very common issue.
4/25/2010 4:45:33 PM EDT
[#14]
Quoted:
Could someone tell me the difference between the Mil spec and commercial version of the CTR Stock


The inside diameter of the CTR varies on mil-spec and commercial versions to fit over mil-spec and commercial receiver extensions.  The stocks are otherwise identical with the same features and construction.  Info from Magpul
4/25/2010 11:03:24 PM EDT
[#15]
I have a mil-spec CTR on a Spikes extension that sticks on the closed position as well.  It seems to only stick if it has been closed a while though.
4/28/2010 5:09:26 PM EDT
[#16]
I just received an ACS stock for this build and it does not stick to the threads like the CTR does. In case anyone was wondering...
4/29/2010 2:27:11 PM EDT
[#17]
Quoted:
Quoted:
The stock is probably getting caught on the threads of the receiver extension.
I had the same issue and lightly beveled the inside leading edge of the stock with a round file and fixed the problem.

Took all of two minutes.

This is the correct answer.  On a mil-spec tube, the threads are thicker than the tube.  The stock is sized to fit the smaller diameter tube.  The solution is to take a file - preferably a rounded file such as for wood working, and bevel in the inside edge of the CTR.  It'll take a few minutes, but not difficult.  

I'm a little disappointed Magpul doesn't do this already, as this is a very common issue.

We don't do this because the threads themselves in this area are supposed to be milled down...
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