AR builders -- what is this?

[Whisper]

I need some help from someone who has a wider range of experience building ARs than I do.

Somewhere along the line I acquired the free-float handguard pictured here; purchased at some gun show probably a couple of years ago.  I'm now doing a build in which I can use this handguard.   However, when I purchased it I did not notice that it uses an odd barrel nut, as you can see here.  

Anybody know who made this handguard?  There's no maker's name anywhere on it.  And, what am I going to use to torque this barrel nut?  I have a two-ended barrel wrench but neither end will fit this.

Thanks,

Whisper

[gjohnsoniv]

Strap wrench.

That's me being a smartass. I'm guessing there was probably a special wrench that came with it. 

Edited August 2, 2017 by gjohnsoniv

[Whisper]

Strap wrench is all I can think of unless someone knows the brand of this barrel nut so that I can see about getting a wrench that will fit it.  The problem with a strap wrench is measuring the torque value.

[Chucktshoes]

Are there any markings at all on the rail? Can you post a picture of the full rail? It looks familiar but I'd like a full view before I start looking at some of the options. 

[Whisper]

It's completely unmarked.  I was told it was a Diamondback but it doesn't look to me like anything on the current Diamondback website.

Thanks,

Whisper

[Chucktshoes]

I'm not finding that barrel nut or rail anywhere. I have a feeling the rail istelf was probably discontinued. The proprietary rail attachments is my clue there. Most everything is dickmod or Mlok at this point. I was trying to find a rail with matching nut, but there are just infinite options it seems. Everybody has got to be different.  Sorry. The strap wrench may be the only viable choice. 

[bruiser09]

The pitch of the teeth looks too fine for a common spline socket. I'm counting 42 teeth there?

You might be able to improvise a crows foot socket as you don't really need every tooth engaged.

I did a quick CAD drawing showing how the outside diameter of the nut need only intersect at strategic points, i.e. I'm showing 4.

If you trace the nut on to a flat piece of sheet steel, then drilled 4 holes to accept roll pins the diameter of the pitch, followed by drilling the outer diameter to intersect the 4 holes you could then grab the steel with Vice Grips and give it some serious torque. (30 to 80 ft/lbs according to the net)

If you could cut the 3/8" square you could use a real torque wrench.

Sorry to be lengthy, but it's an option.

[gjohnsoniv]

^That's a plan.  I'm going to go dig in my tool bag real quick, I'm thinking I've seen a funky wrench end that might work.  counting 42 teeth as well.  Ultimately I don't think I'd worry about the torque value that much, mil spec nuts have a huge value range.

[bruiser09]

A die handle with right angle threaded bolt might work if you found one close enough to size, and the bolt was long enough to grab the nut.

[gjohnsoniv]

Couldn't locate what I was looking for.  What about drilling part way in to grab with a spanner?

[bruiser09]

Drilling the tool (spanner)? Yes. Probably require a cobalt bit.

Drilling the barrel nut? I wouldn't do it, wouldn't advise it.

In a pinch, I'd use vice grips and a patch of leather on the jaws to protect the surface, being carful not to apply so much pressure that the nut is damaged.

BTW, if you decide to try the strap wrench, maybe you could apply a steel hose clamp to the nut first, to give an oblong shape for better bite.

There is a kind of strap wrench that uses a bicycle chain. About $23 at Home Depot, made by Crescent called a chain Wrench. Go figure.

[mikegideon]

I can't find a picture of that thing anywhere. If I was going for much more than a sloppy blaster gun, I would probably just cry twice and get a name brand part. I'm on the snobby side when it comes to handguards anyway. I'm not about to stick a barrel on a rifle without the right tool.

Now, the way to put torque on a smooth round surface without dinking it up is a barrel vise. That may work in place of the right tool.

I picked this on the last 3 builds. Love 'em. BCM dickmod...

https://www.bravocompanyusa.com/BCM-KMR-ALPHA-13-KeyMod-Free-Float-Handguard-p/bcm-kmr-a13-556-blk.htm

[Whisper]

Thanks to all for your suggestions -- especially to you, bruiser09; making CAD drawings is really beyond the call of duty.  I appreciate it.

Yes, the nut has 42 teeth.  I agree it probably requires a proprietary nut wrench, which was why I wanted to see if someone could identify the maker.  I've seen a fair number of barrel nuts before but nothing like this.

The problem with the idea of strap wrenches, chain wrenches, vise grips with leather pads, and barrel vises is that none of them offers a way to measure torque.  I'm not worried I can overtorque this nut with a strap wrench, but I do want to make sure I can reach minimum torque.

If we can't identify the maker, I'll probably throw this into the vise, tighten it as much as I can with vise grips padded with leather, and then fire the first few rounds through the gun from behind a barrier.

Thanks again,

Whisper

[Dolomite_supafly]

Rather than Vice grips I would use a pipe wrench, they are designed and work better on round things than a wrench or pair of pliers. With a pipe wrench the more pressure you apply the tighter the wrench grabs the nut. A strap wrench will NEVER get the nut tight enough, at least not one you would find at Home Depot.

As long as the nut is tight without the chance of it backing off the torque values are not as important. I have built quite a few AR's before I had a torque wrench and never had an issue.

7 hours ago, bruiser09 said:

Drilling the tool (spanner)? Yes. Probably require a cobalt bit.

Drilling the barrel nut? I wouldn't do it, wouldn't advise it.

In a pinch, I'd use vice grips and a patch of leather on the jaws to protect the surface, being carful not to apply so much pressure that the nut is damaged.

BTW, if you decide to try the strap wrench, maybe you could apply a steel hose clamp to the nut first, to give an oblong shape for better bite.

There is a kind of strap wrench that uses a bicycle chain. About $23 at Home Depot, made by Crescent called a chain Wrench. Go figure.

I seriously doubt that barrel nut is so hard it requires the use of a cobalt bit. Hardening adds quite a bit to the cost and that rail looks like typical cheap rail so it is probably not hardened.

[peejman]

What he said.... pipe wrench and wrap the nut with leather or several layers of foil tape. 

It looks thick enough that you could grind some flats to make it easier to grip. 

Edited August 2, 2017 by peejman

[Whisper]

Pipe wrench with leather pad -- better idea than vise grips.  I bet I can hit the minimum torque value with that.

I'll be paying more attention to barrel nuts when I buy rails in the future.

Thanks again for all the suggestions.

Cheers,

Whisper

[MacGyver]

Have you done a loose hand fitting of the nut on to the receiver to see if the threads match?

I think you've got a cheap airsoft part. Your mileage may vary trying to put it on real steel. 

[Whisper]

16 minutes ago, MacGyver said:

Have you done a loose hand fitting of the nut on to the receiver to see if the threads match?

Yep.  Fits fine.   Also, barrel nut is steel -- not what I usually associate with airsoft parts.  But I don't know anything for sure except that a standard barrel wrench won't fit it.

 

Edited August 2, 2017 by Whisper

[mikegideon]

23 minutes ago, MacGyver said:

Have you done a loose hand fitting of the nut on to the receiver to see if the threads match?

I think you've got a cheap airsoft part. Your mileage may vary trying to put it on real steel. 

Real aluminum.  

[mikegideon]

12 minutes ago, Whisper said:

Yep.  Fits fine.   Also, barrel nut is steel -- not what I usually associate with airsoft parts.  But I don't know anything for sure except that a standard barrel wrench won't fit it.

 

In that case, slather that sucker in red loctite and give the torque your best guess. Torque won't matter much if the barrel ain't wobblin. Best part... you will know the required removal tool. Propane torch.   

[MacGyver]

I'd spend some time on AliExpress. I'd be surprised if it doesn't yield answers.

Are there no markings on the handguard anywhere?  That's generally an indication of an airsoft part - as they're trying to keep from getting confiscated for infringement at customs.

 

[Whisper]

Well, well -- look here:

https://www.classicfirearms.com/diamondback-rail-10-5

Apparently it really is a Diamondback rail.  Also, the review on this page mentions the issue with proprietary barrel nut.

Cheers,

Whisper

[gregintenn]

I have a Midwest industries handguard with a similar barrel nut. You are welcome to borrow my wrench if that turns out to be what it is.

[Ronald_55]

15 minutes ago, Whisper said:

Well, well -- look here:

https://www.classicfirearms.com/diamondback-rail-10-5

Apparently it really is a Diamondback rail.  Also, the review on this page mentions the issue with proprietary barrel nut.

Cheers,

Whisper

This wrench looks close to the nut.

https://monstrumtactical.com/collections/free-float-quad-rail-handguards-ar-15/products/ar-15-armorers-wrench?variant=15621769091

I tried looking on DB's site and there is no link to a wrench to buy from DB. If you Google, you get a dead link to the page it is supposed to be on. I am guessing they moved to standard barrel nuts maybe. Looks like you might be borrowing theirs. 

"Rifle Accessories – tagged "HANDGUARD" – Diamondback Firearms

https://diamondbackfirearms.com › Rifle Accessories

DB15 Custom Handguard Wrench. $ 29.99. DB15 HANDGUARD WRENCH ... DB15 Gen 1 Barrel Nut &Jam Nut. $ 19.99. DB15 GEN 1 BARREL NUT AND JAM ..."

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjZzdbXkLnVAhXDJCYKHa9KCDQQFggmMAA&url=https%3A%2F%2Fdiamondbackfirearms.com%2Fcollections%2Frifle-accessories%2Fhandguard&usg=AFQjCNEhK93Lw_7EnpS662G1gp3eyjRXsw

[MacGyver]

20 minutes ago, Whisper said:

Well, well -- look here:

https://www.classicfirearms.com/diamondback-rail-10-5

Apparently it really is a Diamondback rail.  Also, the review on this page mentions the issue with proprietary barrel nut.

Cheers,

Whisper

Cool.  That review was funny.  I bet loaning the customer a barrel wrench every time is a pain...