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Posted: 11/5/2005 7:14:03 AM EDT
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One of the sherriff deputies pulled up yesterday eve and ask me to look at his AR to see why isnt holding a group. Well I told him it wasnt much I proboly could do but I would mess with it today. I was thinking the barrel was wore out or bad ammo selection. This morning I took it down to clean it before I took to the range and I though I felt the barrel move when I was wiping down the FSB. So I poped the hand guards off and sure enuff the barrell was lose. It wasnt really lose but it had some twisting play and a little up and down. I tought When I built my last 2 there was a noch to prevent twisting and to line the barrel up vertically. Im going to take it apart in a little bit , do yall think I can just retoque the barrel and it will be ok? Thanks |
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I once purchased a complete upper that didn't group that well, but I lived with it. Eventually, I took it apart and sure enough, the barrel nut was loose and being retained only by the gas tube. Never once had function problems, the rifle was 100% despite the barrel being able to be jiggled around much like you describe. I re-greased and torqued the barrel nut properly, and the rifle is now exactly as accurate as it should be. Very significant improvement in precision. The bbl nut originally was slightly less than hand tight... when torqued, the barrel nut had moved to the next notch. My index pin and upper receiver index pin notch were undamaged. Make sure your index pin and notch are 100%. If so, re-install that barrel and see what happens. Edit: Oh, the supplier of my improperly assembled complete upper? Gunsmoke Enterprises. They're on the Fucko List now. |
I would guesstimate about 1000-1200 rounds. As for torque values, I use the hand-tight-then-advance-to-the-next-notch barrel installation method, so I can't tell you anything about the real torque values. The method is well established here, and you don't have to reconcile various wrench types, grease types and arm lengths. Some people refuse to use this method, and some people refuse to use anything except this method. Both give you pretty much the same result. If we talk about it too much, though, it will start a Chrome/non-Chrome - Ford/Chevy - Coke/Pepsi style flame war. Wish I could provide more specific info for you. 
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No need to go into anymore detail. Thanks for the info! |
| IIRC the barrel nut torque range is 31-80 ft-lb. However, IIRC, this is with the USGI wrench which has a few inches of added distance from the axis of rotation. Torque = force * distance. If you use any other method of tightening the barrel nut (I.e. different wrench or something) your mileage will vary! |
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