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Posted: 11/23/2013 2:17:00 PM EDT
| How tight is too tight? I'd like to avoid tightening my nut too tight and ruining something. I am trying to install a MI K Series Keymod and they recommend 30 - 60 ft-lbs and no more. Problem is I get slightly past gas tube alignment at 30 and the next groove doesn't come into place before I get to 60. I've been looking foreward to this installation for two days. Why is tech support always closed on weekends? |
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This:
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Did you follow the torqueing procedure? Tightening to 30 ft. lbs and loosen. Do this 3 times, then try for alignment with between 30 & 80 ft. lbs. For my YHM rail install, I was having the trouble you described. I tightened the nut to 60 lbs and loosened it 3 times to set the threads, and It lined up perfectly at 45lbs after that. You can also play with the amount of grease if setting the threads does not have the desired effect. |
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Grease does not compress - If it is gooped up like a peanut butter sandwich perhaps a little cleaning will give you the needed clearance -
On a couple of my builds I put a dab of valve grinding compound on the face of the bushing and nut and give it a dozen good turns to take off the high spots - Clean it well and try again - You can achieve proper torque with a 3/8 wrench - Good for you for not going crazy with it - (I screwed one receiver up learning this) |
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The grease is to prevent galling with steel vs aluminum.
The 2 materials do not play well nicely together. Worry less about torque or more about alignment and do exceed 80ft/lbs. Some are really tight... some aren't... it depends on the threads and thread length. |
| DING! DING! DING! We have a winner. FALARAK discribed what worked. Honorable mention goes to those before him who mentioned repeat torquing and higher torque values. I went back and torqued to 60 and then backed off almost all the way. I repeated and saw that it got closer to alignment though still torqued to 60. The third cycle got it nearly there so that I used my dandy Gem State Armory wrench to take it home. My burnt bronze build is completed! http://www.runemasterstudios.com/graemlins/images/jive.gif Look for photos soon. |
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Easy fix. There are shims that go between the barrel and receiver ( got mine at spikes) that allow for propper gas tube / barrel nut alignment without over torquing. I was approaching 90 ft lbs and was still off. After the shims, 38 lbs....GTG.
http://www.spikestactical.com/new/ss/rail-accessory-barrel-nut-shim-kit-p-605.html |
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30-80 ft. lbs It's a wide spec.  Quoted:
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How would yall feel about a barrel nut only torqued to 32 ft lbs? And if it was torqued/loosened the three times to 32 ft lbs as suggested? 30-80 ft. lbs It's a wide spec. Yup. As long as it's at least 30 but not more than 80 ft. lb, I'd be just fine with it. I haven't come across an upper/barrel/barrel nut combination that was that low, not yet anyway, but I have certainly seen a few that "torque/loosen/repeat," over and over, made a huge difference in how far around that nut went. |
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