YHM Free Float Torque findings

[Cmaro21]

I was wondering if anyone has had any issues with Yankee Hill Machine free float hand guards. This isn't a huge deal but I feel that I am having to tighten these too much. In the YHM included instructions they don't provide torque specs. This doesn't matter too much so I just attach my barrels per the Marine Corp Tech Manual specifications and some knowledge provided by Midway. This happened to me twice, the first time this happened I thought it was a fluke, the second time I thought it may be the YHM Barrel Nut, just looking for a second opinion here.

My procedure -
Torque to 35 ft-lbs
Loosen
Torque to 35 ft-lbs
Loosen
Torque past 35 ft-lbs until gas holes line up, not past 80 ft-lbs.

If I left the barrel on with the second Torque to 35 ft-lbs, the gas holes are in perfect alignment. When I go past the 35 ft-lbs to 36, the holes is just out of alignment, I increase by 5 ft-lbs until I can get them to align. I got up to 70 ft-lbs and it still wasn't there but am very close so I only increase 1 ft-lb each time and check. The last two I installed hit exactly 78 ft-lbs when I could get the gas holes in alignment. That is 43 ft-lbs of torque past the minimum and 2 from the max. I haven't had this with a standard Colt Barrel nut assembly, just with the YHM barrel nut provided for their free float hand guards and both aligned at 78 ft-lbs (79 or 80) would allow for a better match of the freefloat upper rail the lower's rail but I didn't want to to go any further than was needed.

Your experience and input on this is appreciated.

Thanks,
Cmaro

 

[G30]

I found the same....I built three AR's using the TD tubes and they all took right around 75 ft lbs, didn't bother me though Id rather have it near the max than min. When you say you increased 5 ft-lbs at a time, was this just adjusting your TR another 5 and continuing turning? I'm sure you know this but to get a true reading you need to do one continuous movement until your end point, if you "bump" it up 5 at a time it won't be accurate at the end. What are you lubing with?

 

[icyclefar]

With every torque and release you are stretching the assembly.

Sometimes just leaving the assembly under tension and coming back to it the next day will get you there.

And as said above, set the TR and crank it in one time, DO NOT bump it up incrementally.

Did you coat the threads with anti seize?

 

[Cmaro21]

Thanks for the replies. I clean up the thread with a brush and a little machine oil and then apply a thin layer of anti seize before the assembly. If the wrench breaks and the gas hole isn't aligned I back the nut off, + 5 to the wrench and go at it again. Rinse and repeat until I go up to 70 ft-lbs and I was real close, then I + 1 ft-lb. I was worried that I was stressing the upper too much and I didn't want to strip the threads but it seems like I am in an ok range and others are too. Is there a better way to tighten the barrel?

Thanks

 

[G30]

You will break the receiver before stripping those threads. There's quite a debate about anti seize corroding AL, I just use white lithium grease. If you have it properly secured in a receiver block and torque in one motion as you say you do, there really isn't a better way.

 

[Cmaro21]

Thanks for the input. I never hear stressing or any noise from the metal so I keep going until it clicks, never to exceed the 80 ft-lb max. If I were unable to align the gas holes are there any spacers made, like a washer, that I could place between the two to try and get the alignment needed? I am just looking ahead for the future.

Also, is the ant-seize bad enough for me to strip down my upper, clean up and reassemble with white lithium grease?

Thanks,
Cmaro

 

[G30]

There is no hard evidence, just a lot of bickering back and forth on other gun forums about the corrosive nature of some of the anti seize stuff out there, so I just played it safe with the WL. You really can use any good bearing grease. I wouldn't strip it down..just next time use something else. You should never have to shim the barrel/receiver fit.

 

[icyclefar]

Anti-seize is specifically designed to be used with dissimilar metals, (aluminum receiver / steel barrel nut) and to the best of my knowledge there are no metals excluded for its use.

I've been using it for decades in hundreds of different applications without any ill effects.

 

[G30]

Like I said it's debated. It's the graphite in the anti seize that, when compressed between the two dissimilar metals, as you said, (AL and steel), will cause problems, and most of the big brand popular compounds have graphite in them. The most I saw as "fact" was a few studies showing that over time the graphite will in fact corrode the AL (this is assuming some of the anodizing was scraped off in the torquing process). Of course there were 10 people saying they never had an issue for every 1 person saying it's instant death, just thought I'd throw it out there. I prefer WL because it's more available, cheaper,and less messy than AS compounds...but they all work.