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Posted: 8/19/2006 6:15:07 AM EDT
| When installing a new barrel, how is it supposed to be torqued? By that I mean how should the adapter be installed on the torque wrench? I have always been taught that when using any kind of adapter that adds length to the torque wrench you should install the adapter 90 degrees to the torque wrench so that you get the correct value. But after looking at the Army TM(9-1005-319-23&p) the illustration shows the adapter installed in-line with the torque wrench and has a note saying that the proper torque is attained when the wrench and adapter are used together. I'm about to put a new barrel on my upper and want to make sure I don't under/over torque the barrel nut. Any clarification on this would be greatly appreciated. |
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Moly grease (read brake shoe/pad grease) the threads of the upper socket/ barrel nut, and make sure to grease the contact lip of the barrel extension and the inside of the barrel nut where the two will mate. Tighten the barrel nut to 35 lbs, then back it off, tighten again then back it off a second time, then on the third time hit the 35 lb mark, and set the torque wrench to 79 lbs (don't tighten any father yet over the 35 lbs). Now using a rod or the gas tube, check the top spines on the barrel nut to see if the valley between them is dead center of the upper's hole for the gas tube to pass through. If needed, tighten the barrel nut slightly more to correctly index the barrel nut for the gas tube, but stop if the wrench hits the 79 lb mark before the nut is indexed for the tube. If you do hit the 79 lb mark, then you will need to back off /retighten it the nut a few more times. The reason for the initial tightening is to mate the barrel nut with the upper barrel socket threads (so the nut doesn’t come lose in a few hundred rounds), and the reason for the couple more if needed after the 35 lb mark is the same (read will allow the fraction more of a turn without hitting the max torque value). Again, make sure to correctly grease the parts are you will get a false reading. |
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