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Posted: 1/15/2016 3:10:21 PM EDT
| When the barrel nut will not allow the gas tube to line up when you torque it down properly causing over or under the suggested torque range, what is the fix? I tried a 2nd barrel nut with the same results, so I don't think it is the nut. |
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I did the tighten loosen curse repeat several times with no luck, nothing seated any deeper or changed so I knew one of you had the answer. Thanks!
Looks like the shims are the easiest way of doing it. Will try that 1st as they are fairly cheap and the barrel seats ok just does not allow the gas tube to align between 30-80lbs of torque. |
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Quoted:
Lap the receiver if needed. +1 You get the added benefit of knowing the upper face is perfectly perpendicular to the bore and there will be no high or low spots that might create problems when trying to sight in. There's a reason all the benchrest guys do this to theirs. In case you're wondering how it helps you by removing a few thousandths of material you can advance the nut slightly further to get it to the position you need it to be in. |
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Quoted:
+1 You get the added benefit of knowing the upper face is perfectly perpendicular to the bore and there will be no high or low spots that might create problems when trying to sight in. There's a reason all the benchrest guys do this to theirs. In case you're wondering how it helps you by removing a few thousandths of material you can advance the nut slightly further to get it to the position you need it to be in. Quoted:
Quoted:
Lap the receiver if needed. +1 You get the added benefit of knowing the upper face is perfectly perpendicular to the bore and there will be no high or low spots that might create problems when trying to sight in. There's a reason all the benchrest guys do this to theirs. In case you're wondering how it helps you by removing a few thousandths of material you can advance the nut slightly further to get it to the position you need it to be in. brownells sells the tool and compound its simple and makes a huge difference. |
| Or just lap a very small amount off the front of the receiver using 320 Wet-or-Dry abrasive paper on a piece of glass or your granite counter top. Wet the paper with WD-40. Grip the receiver between your thumb and first finger and move across the paper in a figure 8 motion while exerting a light downward pressure. Only remove enough material to just barely lap through the black anodizing. Refit the barrel and see what you get for alignment while torquing up to 80 lb-ft. Repeat as required until the barrel nut aligns with the gas tube hole in the receiver. The Brownells tool is great but an unnecessary expense. |
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Quoted:
Barrel nut torque is listed as 30-80lbs, it is inconceivable that you cannot get the gas tube to line up within that torque range. V Exactly. I just installed one yesterday. At 30 a tooth was right in the center of the hole, turned it to 35 and it lined up. |
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The reason why we have torque values is because the Army loves numbers and data. If taking the barrel nut off and on again repeated times, it should get easier to align. You could also go over 80# and be fine. Going from 30 to 80# is a decent enough range to get the nut aligned. I really don't understand how it's not working for you. I can't count how many times I've torqued to 30 and moved an e tire hole over and not even reaching 80#. |
| Lapping the front of the receiver on top of a table with a sheet of sandpaper does nothing to make sure the front of the receiver is kept perpendicular to the center line of the action. That is the main purpose of the lapping tool, to not only make the face of the receiver flat but to keep it squared/perpendicular to the center line of the bore. Lapping it flat on a table top does nothing for squaring the face to the center line of the action, and in fact, can make it worse. You might have a flat surface on the front of the action but without the lapping tool's guide to keep you square you could be flattening the face several degrees off square. |
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