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NewARBuilder87

To tighten, or not to tighten...

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On my 2nd build now, I'm at the point of installing the handguard, as I'm trying to tune it to where the rail lines up, I get ever-so-close, but hit a wall. Now if I loosen it to where it lines up, it'll be under-torqued, but don't know if I should push it tighter so it'll line up. So I'm at an impass at what to do, open to suggestions. I'll attach a pic of how close it is at the wall.15b8e5ae07e5fbc66f7f9a618651dfcd.jpg

 

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Back the nut off once or twice and re-torque...it will get there.

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Definitely do something with the nut be it back and forth, a shim or two, etc. This could start a war but I'll ask; did you lube the threads on nut/ rcvr?

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Back the nut off once or twice and re-torque...it will get there.

This, its very common to tighten it then back it off a d retighten it several times.

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I am offering an idea as well as asking a question here.

I could be wrong here, and if I am someone correct me.

If that nut is also the barrel nut and not just another nut.

BUT. Isn't the torque range of the nut fairly broad? Something like 20 - 80 ft lbs? Have you tightened to the 80 lbs yet?

 

Darrell

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Yes, the barrel nut has a pretty broad torque range. But if for some reason you can't get within that range, you could try shims. Use the thinnest shim(s) needed to get the job done.

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Lube, yes, haven't tried shims, they'd put the nut too far forward from the receiver, making the handguard have a space between itself and the upper. I have also tried the tighten, loosen, tighten, etc method and got so close it hurts, but still a little short. I'm gonna throw my idea out there, knowing I'm probably gonna get chewed a new one for it, but I've been thinking about getting out ye 'ol dremmel and shaving the barrel nut 1/16th. That'd solve my problem I'm sure, but want to know why I shouldn't. Thanks again y'all, always so helpful, I don't mind any advice or critiques y'all have for me, I learn every day

 

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If your going to cut the barrel nut that will put it too close and your guard will hit the upper...also if you were to do it it needs to be lathed perfectly straight and not Dremmeled.

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My only suggestion is to lube it up with some white grease, and torque that bad boy on there. Again, back and forth with the nut if you need just a little more. The only thing I would try if that does not work is to have the receiver squared. They sell tools that you can buy that will square up the receiver and you can take a little or take a lot away depending on what you need. I would try that and take a little and try the nut again...rinse and repeat until it fits.

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At this point, I'm beyond torque range, it simply won't go any tighter, not without risk of cracking the receiver. I'm really almost out of ideas, disappointed I'm having such a time getting this rail installed. Now the last 2 pieces to the build, BCG and CH, will be here later today for the BCG, sometime tomorrow for the CH. If I could find a machinist with a lathe, I could take 1/16in off the barrel nut without any negative consequences, I hope? Thanks again everyone for your input, one day I'll get through a build without any issues... ONE DAY...

 

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At this point, I'm beyond torque range, it simply won't go any tighter, not without risk of cracking the receiver. I'm really almost out of ideas, disappointed I'm having such a time getting this rail installed. Now the last 2 pieces to the build, BCG and CH, will be here later today for the BCG, sometime tomorrow for the CH. If I could find a machinist with a lathe, I could take 1/16in off the barrel nut without any negative consequences, I hope? Thanks again everyone for your input, one day I'll get through a build without any issues... ONE DAY...

 

Sent from my LM-X210(G) using Tapatalk

You don't need that much material removed. I would try lapping the receiver as you only need approx. .003" of material removed. Think about your 1/16" number for a second.....if your hand guard hits the upper now what's it going to do after you cut that nut? The receiver threads are 18 threads per inch.....you only need about 1/32 of a turn or 1/32 of an 18th inch.

 

If squaring the receiver did not get it there I would buy a shim kit and shim it back to the next set of holes. The gap at the rail to upper will not be big enough to care about.

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I have not seen mentioned elsewhere but I did this on my last barrel install and it worked more smoothly.

 

Put some grease on the front flange of the barrel extension where the barrel nut contacts and a little in the barrel nut where it contacts this flange as well as the threads on nut and receiver.

 

Then tighten and loosen repeatedly as others have suggested.

Edited by bj139

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Cutting on the end thread end of the barrel nut will not accomplish anything as the mechanical interference is the inside shoulder.

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Not too sure what you mean by that, but I'm here to report that the problem is resolved!!!

Cutting on the end thread end of the barrel nut will not accomplish anything as the mechanical interference is the inside shoulder.

I ended up just trying the barrel nut on another stripped upper I had on my 3rd builds upper/lower, and it ended up being able to line up nicely, while still being tight enough, and barely... Because, through much internet surfing, I discovered this type of barrel nut is common among free floating handguards, so slight topic change, I'd like anyone's take on the handguards the have the 2-5 screws all tightened on the under-side of the handguard towards the receiver. I'd hate to run in to this issue with that type of handguard which I prefer, so I'm willing to hear pro's/con's of handguards that attach in other methods besides screwing in to the barrel nut directly. Thanks again everyone for all your help and opinions, y'all make me a better builder every day!!!

408

 

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