Torquing your Diamondhead FF Rail to Spec

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willywonka519

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Alliston, ON
So picked up one of those decently priced Diamonhead rails for my 11.5" build, threaded on the barrel nut, then thought......how the **** am I going to torque this to spec?

The barrel nut is basically a large 1 and 1/4" hardware nut.

I'm not a "tools guy" by any means, so it took me a while on the interwebs to figure out what I needed was to attach a 1 and 1/4" Crowsfoot wrench to my torque wrench to do the job.

Then it took me a good portion of my day off to drive around and find that nobody stocked such a device, unless I wanted to pay $89 for a set at Princess Auto.

I finally was able to have the Crowsfoot ordered from a tool shop in Hamilton (Teg's Tools) for a grand total of $30.

I'm fairly confident this will allow me to torque the barrel nut to spec, and if anyone was wondering the same thing with their Diamondhead rail, I will update with pictures once the Crowsfoot comes in.

Also, if your close to Hamilton, ON and want to borrow my Crowsfoot and upper receiver block, PM me, drop by and you can borrow it for a tall can :D
 
i did mine by hand. torqued it until it wouldnt torque much tighter without breaking it. just aligned the hole for the gas tube. 1000+ rounds without issue and bolt is not wearing funny along the gas tube.
 
I did mine with a receiver block and after putting on some anti-seize, I used a big crescent wrench to tighten it down, not excessively but firmly. At a 12" length about 5 pounds of 'weight' pushed on the wrench should get it up to 60 inch pounds, considering what a wide range of torque the barrel nut is rated for (30-80 inch pounds) I'm not worried about hurting the threads.

Plus the handguard has the anti-rotation tabs so even in a worst case scenario, it can't actually rotate out enough to loosen the barrel nut.
 
Hmm.....so the crowsfoot tool was probably a bit overkill.....

My main concern was not torquing it enough to ensure the barrel extension was properly in place. As this is my first AR build, I'm pretty cautious about headspace issues, barrel nut torques etc.....
 
willywonka519 said:
Hmm.....so the crowsfoot tool was probably a bit overkill.....

My main concern was not torquing it enough to ensure the barrel extension was properly in place. As this is my first AR build, I'm pretty cautious about headspace issues, barrel nut torques etc.....
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Headspacing absolutely. I spent 80 bucks to get the 5.56 NATO Go and No Go gauges to check headspacing on it.

But the barrel nut torque is such a wide open range. Now really getting the crows foot to use a torque wrench is just cheap insurance that you get it dead on to spec, but the torque range on the AR15 barrel nut is such a wide range that it's kind of hard to mess up, especially once you tighten up the handguard clamp and the handguard can't rotate out at all.
 
willywonka519 said:
I've heard a few people who are for and against buying the headspace gauges.......I figure that I'ld rather drop $80 and make sure I don't blow myself up....haha
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Yep, 95% of barrels will work with 95% of bolts (Honestly it's probably more like 99% of both), but if the tolerances stack up just right then you can have an issue in headspacing, worst case you blow the barrel or have a case head separation, best case your gun runs like junk.
 
F22_RaptoR said:
I did mine with a receiver block and after putting on some anti-seize, I used a big crescent wrench to tighten it down, not excessively but firmly. At a 12" length about 5 pounds of 'weight' pushed on the wrench should get it up to 60 inch pounds, considering what a wide range of torque the barrel nut is rated for (30-80 inch pounds) I'm not worried about hurting the threads.

Plus the handguard has the anti-rotation tabs so even in a worst case scenario, it can't actually rotate out enough to loosen the barrel nut.
Click to expand...

Foot pounds not inch pounds.
T
 
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