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AR15 Handguard - How is it kept tight?

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I'd like to install one of those fancy machined handguards with the Picatinny rail along the top to one of my phantom AR-type rifles. The original barrel nut is toothed, and the gas tube through the teeth is what keeps the nut tight. These new handguards have a barrel nut that doesn't look to have any teeth to prevent loosening of the nut. What keeps the nut tight? If it's just friction, that doesn't seem to me like it's going to work for too awful long...

barrel-nut.JPG
 
OP
nvshooter
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Maybe some form of Loc-tite?
I'd not want to put loc-tite on those threads. I put a drop too many on the buffer tube threads of another one of my phantom AR-type rifles a number of months ago. I then wanted to install a QD endplate a couple of weeks ago. The castle nut was so tightly adhered to the endplate that the little alignment nub on the OEM endplate rotated with the nut and buggered the threads. A quick hit on the ebay website and about a week of waiting had me a new tube and castle nut. I now use one sparing drop of loc-tite to secure the castle nut.

I have seen these types of handguards offered with two wavy washers. I'd have to assume the wavy washers are what maintain friction once the barrel nut has been tightened. I'm a mechanically-minded person. I prefer nuts and bolts over "modern composite adhesives." One of Boeing's new wide-body jets is glued together. You won't see my assets on that jet...
 
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Just read a thread on a forum about using some kind of RUBBERY COMPOUND to hold grip screws in. Its easy to loosen and is reusable. Will try to find the thread and get the name for you.

Merry Christmas!

Didnt find the thread, BUT, did find this on e-Bay:

"Prevents fasteners loosening from shock & vibration
Vibra-Tite VC-3 Threadmate is one of the most versatile threadlockers available on the market. Unlike traditional liquid lockers which cure to form a hard bond, VC-3 is a blend of resins designed to remain flexible and absorb vibration. This unique difference makes VC-3 coated fasteners truly adjustable, removable, and reusable. Great for fasteners ranging from tiny set and eyeglass screws to huge construction bolts, Vibra-Tite VC-3 is ideal for use on assemblies of any size and configuration.
  • Will not harden like traditional threadlockers
  • Dampens and absorbs vibration
  • Works with metal, wood, plastic* and more
  • Fasteners are easily adjusted, removed and reused
  • Works on fasteners of any shape or size, from tiny eyeglass screws to large construction bolts
  • Works with internal or external threads"

The name sounds familiar!!

ps: there are several types/strengths of Vibra-tite, red/blue/purple, and several different products. I'd search for VIBRA-TITE and let them suggest away.
 
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OP
nvshooter
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I have heard of Vibra-Tite. The stuff is supposedly on the inner screw of one of those screw-within-a-screw, trigger-creep adjustment screws that allows for adjustment of mil-spec triggers in AR-type rifles. Green loc-tite may be a solution. The stuff is very watery, and is used to cement very small screws, like we find in electronics. I figger a liberal dripping of the stuff on the threads of the receiver mouth would do just fine. I have yet to order the handguard; have other irons in the fire as of this moment.
 
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Unless you're just a hobbyist/enthusiast, then there are much better options these days than using a Proprietary barrel nut.


Geissele FF's used to be known as bomb proof, but recent developments from US Army Special Operations have revealed that when dropped, there is a significant shift of it's axis. It may not mean much if you don't use an IR laser or a BUIS, even both, but it does to them because they actually do.

If I was you, I would just pay the coin and be one and done and lose the need for a barrel nut altogether. Get the Knight's Armament URX4. If you still insist on a barrel nut, then either LaRue Tactical or Daniel Defense are two good places to begin looking.
 
OP
nvshooter
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you have to torque them down i never seen one come loose yet and ive built alot of them.the worst ive seen is a broken gas key that was way over torqued.
 
OP
nvshooter
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Got a few of these with the tube passing through, if it makes you feel better about it.
I have bought several like your example from Model 1 Sales. Their offerings are kind o' plain, but they do go into place and secure just like the OEM nut. I want one of those handguards that are all machined-out with oddly-shaped holes, a somewhat oval cross-section and light in its weight. I do like the looks of what you show, though. Do you have a manufacturer name and part number for what's in your picture? I like the "military look" of that tube. Looks "all business; no bullschumer." It looks "issue," like what you'd see on a US Marshall weapon.
 
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nvshooter
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You have to torque them down.
I tighten the nut just to where the gas tube will pass through the first tooth of the nut. I am probably not achieving 35 to 80 foot-pounds of torque, but I have to thump the wrench a bit with a fourteen-inch piece of 2x2 to get the alignment that's needed. I'd have to assume that's tight enough.
 
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that should work thats why they give such a big spread.those hand guards are all old school probably over 10 years.really not sure who manufactured them.the new ulta slim guards we have now are nice be it key lock or m lock.
 
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IMG_1217.JPG i built this a few weeks ago 6.5 grendel it sports an ulta slim hand guard and has a nut like your first post it holds 3/8 groups at 100 yards.
 
OP
nvshooter
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Ordered one of those super-ventilated handguards. With it arrived three wavy washers and a bunch of other parts. I can only guess the wavy washers are what keeps the barrel nut tight. We'll know when comes the time to disassemble the OEM set-up and install all of this new, hi-tech stuff...
 
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nvshooter
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Those shims are for lining-up the holes for the handguard when the nut is torqued.
The set-up looks to me to require the barrel nut to be torqued such that the holes in the nut will align with the holes in the handguard. I have used barrel shims in the past to get the nut tightened such that the gas tube passes between the teeth of the barrel nut. Lacking the shim, I could not get a good tightening. The nut was either rotated to such a point that the gas tube would have to go right through a tooth of the barrel nut, or was rotated back too much and the whole handguard system would knock back and forth to a small degree. We shall see how this wavy-shim system works out...
 

Joe Link

Staff Member
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Yep, gotta use the shims and try to estimate where you'll need to have the holes lined up once it's properly torqued. It's a bit of a pain, took me an hour of loosening and re-torquing to get it right on my latest build. If it's off even a little bit the top picatinny rail won't line up with the rail on the top of the upper.
 
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nvshooter
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Just ordered a barrel nut wrench for my new handguard. Made a mistake; ordered one with a 1-3/16-inch opening. Need one with a 1-1/4-inch opening. Saw the second one just a few minutes after completing the order for the smaller wrench. Sent a message to them about the error; hoping they can pull the order before it goes onto the truck. Mentium ships orders via USPS, so the truck will most likely not arrive until 1600 CST. Order was placed around 1400 CST, so there is a chance the seller can terminate the order before it is shipped. If not, I'll have to go through the bullschumer to send it back with an RMA and pay the postage. Why is it the seller can send things to me for so much less than I can send things back to them? I've seen this a few times, and it has me scratching my balding head...

 

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