Torque recommendations?

[Trumpet]

Ok,
So I'm gradually putting together my Grendel upper. I plan on using an Odin 18" barrel, and I'm using a 13" Geissele SMR. Now, Geissele recommends 40 ft/lb for their barrel nut. However, I've been reading a bit and it seems that 6.5 Grendel benefits from a higher torque setting (I see 60 ft/lbs is a common one). If I go that high, will it hurt the Geissele nut in any way? Would the torque to 35 ft/lb, then back off twice, then up it to 60 ft/lb be the way to go?

[NugginFutz]

In all cases, when in doubt, go with the manufacturer's recommendation. The 40 - 60 ft/lb has always been established as a means to account for the barrel nut's being clocked to align with the gas tube. Mine always seem to line up right at 30 lbs. So, on to the next hole and ~50-60 lbs. In the case of those barrel nuts without slots or holes to align, by all means go with the manufacturer's torque #'s.

I don't recall reading any place where builders have been recommending higher torque #'s as a means of getting better accuracy, whereas I have read from several people writing about lapping their receiver for better mating surfaces.

If you do decide to exceed Geissele's recommended torque, then the tighten, loosen, tighten, repeat until desired # is reached would be the way I would do it.

[Trumpet]

Well, I've seen Bill Alexander state that the torque shouldn't be any less than 60 and John Holliger won't go lower than 50. I've read that Grendel is a different animal from 5.56 and shouldn't necessarily be treated the same in regards to torque values.
ETA: I just PM'd Geissele to see what they say in regards to extra torque on the SMR barrel nut.

[Texas]

The milspec on 5.56 was 50-55 ft/lb.

[Klem]

There's a wide range of acceptable barrel nut torque values for a standard MILSPEC barrel nut; 35-80ft lbs. I have also read 30-80ft lbs. As Nuggin says, this wide range is all about permitting the barrel nut teeth to clear the hole in the receiver so the gas tube can go into the receiver without interference.

Not many free floating handguards need such a wide range as they don't have gas tube holes and teeth to line up. There are exceptions however, for example Samson uses a standard MILSPEC barrel nut. I have also seen a wide diameter Seekins handguard (for suppressors) with holes that need to be lined up for the gas tube. With the rest I suggest you go with the manufacturers recommendations. I have also read some guys believing that tighter barrel nuts result in more smaller groups. I don't believe it myself. Obviously you don't ever want that nut to come loose but cranking it right up could also stress the receiver and have the opposite effect.

One thing you do have to watch is calculating the actual torque value if you use an extension with your torque wrench. Either this or have the extension at exactly at 90degrees to negate the leverage effect.

[jcjarmon]

This is what you need to remember, the barrel nut does not hold the round in the chamber. It only holds the upper receiver and barrel in alignment. So 30 pounds of torque is more than enough if your gas tube is in alignment. Torque the barrel nut to 30 three times, and the third time turn it till you gas tube is in alignment. DO not torque more than 60 pounds. If 50 pounds isn't enough, I would face the upper receiver a couple of thousands with my lathe, or a local gunsmith. You can also use shims, but I have a lathe, so I do it the hard way. Do not put so much pressure on your upper that you crack it. If you have and upper receiver tool, that looks like a long bolt carrier group, you can use it to true up the face of the upper receive. Any gunsmith should have one, but they run about 80 bucks, so most home builders don't.

[sneaky one]

Don't go above 60 if you don't have to, galling of the uppers threads occurs, junk upper rec. then. Really, check the mating surfaces- bbl. to rec. That matters a lot.


I met up with 6.5 Whelen couple years back, we had dinner and did some -trading - , he squared the front of the rec. I handed to him--- was not perfect----- not good enough.

Glad I went this route-- upper shoots fine----------- it will be for sale soon, as a side note . More later as I can post pics. Sidetracked again...


Use the surface insensitive blue locktite-permatex products for the bbl. nut AND bbl itself install. Lube the threads heavy, and the bbl- where it goes into the rec. behind the locater pin.

Tighten down to 30-2 times-40? -then back off to start again..... if you hit 55-58, and still not close? Get a shim kit.

I get Handguards with no timing for gas tube,-------- that's SO new school! Tite to 35 -twice then to 55-60 ft lbs on T wrench. Mop up the smurf blue joooce , let her dry for a few days. Done.

He has the squaring tools for this- contact him if in doubt. LL52 does also. Why buy it , when it's done for a reasonable price--- shipped to your door.

[sneaky one]

Don't go above 60 if you don't have to, galling of the uppers threads occurs, junk upper rec. then.

Aluminum, in the 6000-7000 series is tough stuff,, But the threads can onl take so much torque It's not quite steel!------ 9000 is the Little Giant ladder, and some military apps. Alum.

Really, check the mating surfaces- bbl. to rec. That matters a lot.


I met up with 6.5 Whelen couple years back, we had dinner and did some -trading - , he squared the front of the rec. I handed to him--- was not perfect----- not good enough.

Glad I went this route-- upper shoots fine----------- it will be for sale soon, as a side note . More later as I can post pics. Sidetracked again...


Use the surface insensitive blue locktite-permatex products for the bbl. nut AND bbl itself install. Lube the threads heavy, and the bbl- where it goes into the rec. behind the locater pin.

Tighten down to 30ft.-2 times -then back off to start again.... watch the amount everything changes as for amount of change in relation to where the wrench was a bit ago--- that's the movement of threads, towards the end game--- galling- crushing if past 60 ft lbs.. if you hit 55-58, and still not close? Get a shim kit.

I get Handguards with no timing for gas tube,-------- that's SO new school!

BFT and I built our 2 Faxon uppers in my garage with those style of handguards last summer.

Tite to 35 -twice then to 55-60 ft lbs on T wrench. Mop up the smurf blue joooce , let her dry for a few days. Done.

6.5 has the squaring tools for this- contact him if in doubt. LL52 does also. Why buy it , when it's done for a reasonable price--- shipped to your door.

[sneaky one]

Start anew.... It's simple, to do this .Just don't go heavy on first trial. Always bring a backup dude that knows this stuff.

BFT and I had to practice on a 1" bolt to figure out the torque on his bbl nut, using a t wrench to mimic the setting without a crowfoot attachment of the correct size..--- communication error.

If you feel like you are in an arm wrestling bout, you arm over 60 ft lbs.

Shooting many rounds over time with to much tourqe on the nut will loosen it- accuracy will slowly fade,,

like engine head bolts on a 1997 Caddy, with a Northstar engine with the torque setting 60 ft lbs too high! From the Factory...

The bolts start to gall, then piston up and down pumping oil, then coolant throughout the entire engine. Head gaskets can't keep a correct seal to negate the other fluids transference -- I just told JR to go on the local freeway, keep the speed at 90---- warranty fixes the rest.

Hee hee. She locked up.

[Trumpet]

Don't go above 60 if you don't have to, galling of the uppers threads occurs, junk upper rec. then.

Aluminum, in the 6000-7000 series is tough stuff,, But the threads can onl take so much torque It's not quite steel!------ 9000 is the Little Giant ladder, and some military apps. Alum.

Really, check the mating surfaces- bbl. to rec. That matters a lot.


I met up with 6.5 Whelen couple years back, we had dinner and did some -trading - , he squared the front of the rec. I handed to him--- was not perfect----- not good enough.

Glad I went this route-- upper shoots fine----------- it will be for sale soon, as a side note . More later as I can post pics. Sidetracked again...


Use the surface insensitive blue locktite-permatex products for the bbl. nut AND bbl itself install. Lube the threads heavy, and the bbl- where it goes into the rec. behind the locater pin.

Tighten down to 30ft.-2 times -then back off to start again.... watch the amount everything changes as for amount of change in relation to where the wrench was a bit ago--- that's the movement of threads, towards the end game--- galling- crushing if past 60 ft lbs.. if you hit 55-58, and still not close? Get a shim kit.

I get Handguards with no timing for gas tube,-------- that's SO new school!

BFT and I built our 2 Faxon uppers in my garage with those style of handguards last summer.

Tite to 35 -twice then to 55-60 ft lbs on T wrench. Mop up the smurf blue joooce , let her dry for a few days. Done.

6.5 has the squaring tools for this- contact him if in doubt. LL52 does also. Why buy it , when it's done for a reasonable price--- shipped to your door.

YEah, the Geissele is a no-timing job. Heard from Geissele. Was told that if I have a steel barrel nut, 60 is no prob. If it's aluminum don't go over 50. So go to 35-ish, loosen. Go to 35 again, loosen. Final at 50-ish?

Is the loctite a necessity?

[rabiddawg]

What is the purpose of torquing -loosening torquing loosening torquing?

[jcjarmon]

Aluminum will stretch when torqued to spec. So you tighten then loosen three times to allow the Upper receiver, and barrel nut to conform to one another. Gives you a stronger mating between parts. A steel barrel nut really serves no purpose.

[rabiddawg]

Makes sense.

I just didn't think 35# was enough to stretch the threads, but I'm not a metallurgist

[AZBackcountry]

AR barrel install after Cerakote cropped resize .jpg
I turn my vice and install barrels vertically with a very thin coating of Loctite 243 on the barrel extension & inside the upper mating surface and I use TW25B grease where the barrel nut touches the upper and barrel. I torque per manufactures spec. This is a AR10 Aero Precision M5E1 so it's 65 Ft Lbs and the Magpul wrench has a 2.25" offset so my torque wrench is set at 53 Ft Lbs. { 1-(2.25"/12")X65ft#=52.8125 } Tighten once, back off and make a final torque. Leave vertical for an hour. Wipe off any visible Loctite. Don't shoot for a couple of days so the Loctite is set. I saw every great Gunsmith install bolt barrels vertically, so it made sense.