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2/28/2007 3:59:43 PM EDT
Hey all, my brother is building a rifle and it's completed but there's one problem. He tells me that the bolt/bolt carrier won't fit all the way into the upper. He says that it slides in like it should, and then when it gets to the point where the lugs interlock, it just stops, and if he forces it, it gets stuck. Any help?
Thanks alot,
Tom
2/28/2007 4:37:31 PM EDT
[#1]
His gas tube might be slightly bent.

Look here:

www.ar15.com/forums/topic.html?b=3&f=4&t=317225
2/28/2007 5:13:13 PM EDT
[#2]

Quoted:
His gas tube might be slightly bent.

Look here:

www.ar15.com/forums/topic.html?b=3&f=4&t=317225

+1. Common issue.
2/28/2007 6:00:47 PM EDT
[#3]
check headspace.
3/1/2007 4:58:18 PM EDT
[#4]
Just got off the phone with him, without the bolt in the carrier it works like a charm, so its not the gas tube, and he said he has tried two different bolts with it, and they both do the same thing. Any more ideas?
Thanks again y'all
-Tom
3/1/2007 5:09:35 PM EDT
[#5]
I can't imagine anything seriously wrong. Is your brother sure the bolts not locking up correctly? Is he familiar with AR’s?
3/1/2007 9:43:09 PM EDT
[#6]
does he have the bolt extended when he is installing it?
if the bolt is pushed into the carrier it will rotate and it can't go in.
3/2/2007 5:29:18 AM EDT
[#7]
I'm going back home next friday anyways, i'll look at it and then see if i can see if theres anything that i can see, thanks guys.
oh and I love The Incredibles, just watched it yesterday...
-Tom
3/3/2007 4:32:48 AM EDT
[#8]
K.R.O.N.O.S.
3/3/2007 10:16:59 AM EDT
[#9]

Quoted:
check headspace.


What does headspace have to do with a bolt not locking?
3/3/2007 10:23:11 AM EDT
[#10]

Quoted:
Just got off the phone with him, without the bolt in the carrier it works like a charm, so its not the gas tube, and he said he has tried two different bolts with it, and they both do the same thing. Any more ideas?
Thanks again y'all
-Tom


Based on this - ASSUMING it is installed/assembled correctly:

1.  Trash in the barrel extension/lug area.

2.  Out of spec upper or charging handle, rubbing/obstructing the bolt carrier and/or cam pin.

3.  Out of spec carrier - not allowing the cam pin to rotate correctly.

4.  Out of spec barrel - improper barrel extension install.

5.  Damaged barrel extension, or major burrs on the lugs.


Typically - #1 is going to be most common.  All the rest are going to be very rare... unless this came from a chop-shop AR manufacturer.

DO NOT shoot it if it wont lock.  Find and fix the problem.
3/3/2007 11:11:50 AM EDT
[#11]

Quoted:

Quoted:
check headspace.


What does headspace have to do with a bolt not locking?


i thought he meant chambering a round it didnt close.
thats why i suggested checking headspace.

3/3/2007 11:21:33 AM EDT
[#12]

Quoted:
i thought he meant chambering a round it didnt close.
thats why i suggested checking headspace.



Ahh - yeah - makes sense.
3/20/2007 3:35:01 AM EDT
[#13]
ok, well...i didnt have a camera, but when I looked down the chamber from the back of the reciever, i could see that the feed lips wern't lined up, the barrel was about 1/16th of an inch twisted.
3/20/2007 5:44:58 AM EDT
[#14]
Who made the barrel?  Next step is to disassemble and determine if the barrel extension pin is sheared, or if it was installed improperly.
3/20/2007 6:43:32 AM EDT
[#15]

Quoted:
ok, well...i didnt have a camera, but when I looked down the chamber from the back of the reciever, i could see that the feed lips wern't lined up, the barrel was about 1/16th of an inch twisted.


Wow! Yes, sounds like something is definitely wrong. Follow FALARAK’s recommendation above. See if the index pin is bent or sheared.
3/20/2007 8:10:55 AM EDT
[#16]
I just took it and gave the whole upper to my friend. He's a Navy armorer for the seabees and just got back from Kuait. He said that he'd be happy to fix it for him.
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