Torque Specs

[keystone183]

Anywhere where one might go to find a comprehensive list of torque specs for an ar pattern rifle? I know what most of them are, but a comprehensive list or guide would be helpful.

Secondly, anybody have an idea or guess as to what a good torque value would be on the clamping screws to secure a syrac gas block to the barrel? My first install resulted in turning of the heads. I emailed them this question but have yet to hear back.

[HuntTXhogs]

I have seen torque specs referred to over the years, some low and some high.

What I have experienced via personal trial and error is that torque specs really aren't relevant due to the vast amounts of barrel nuts on the market.

Mega Arms was the best design I was able to apply the high torque spec to it, it really wasn't a shooter once I got it assembled...

I broke, sheared (two holes) a Yankee Hill barrel nut (aluminum) attempting to get to the low torque spec.

I recently read, in my opinion this is based on what I refer to above, that guys are now saying to hand tighten the barrel nut and torque down to the next gas tube hole.


While that is hardly scientific - I put a barrel on last week and with LOTs of effort I took it 2 holes beyond hand tighten contact.

HTXH

[Tedward]

I use a torque wrench on the barrel nut to 30ft lbs. Then add what ever pressure to get to the next hole as required on some model of hand guards so the gas tube lines up. Lots of new hand guards now use a nut so the tube line up isn't relevant. In that case I torque to 60ft lbs. Max. ft lbs. listed with uppers and hand guards I've seen is 80 ft lbs. I've moved to this type barrel nut wrench so I can use my 1/2" drive torque wrench. I mount this in the vice then set the barrel muzzel facing the floor.

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/wrenches/ar-15-m16-combination-wrench-prod468.aspx

Then insert this thru the upper and torque accordingly. Must be catching on, sold out.

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/barrel-tools/ar-15-m16-308-ar-barrel-extension-torque-tools-prod27452.aspx?avs|Manufacturer_1=BROWNELLS

As for gas blocks, yup, no real spec that I have seen and stripping out a allen screw sucks, or breaking the tip of one off. Speaking from experience on that screw up. Since then, I use blue lock-tite and snug them up hand tight. When removing them, you need to use a heat gun and heat it up to free the lock-tite and then your good to go.

Comps or any muzzel device, again a little blue lock-tite then snug it down and and if using a crush washer, I don't use lock-tite.

Not sure on the buffer tube, again, I just tighten till I feel its good, that won't be dangerous as not having a tight barrel or muzzle device. Make sure they are secured properly.

[Keep The Change]

AR-15.com used to have a pdf linked that I bookmarked for the technical assembly manual. I think the manual ID is TM9-1005-319-23.

So if you can find that somehow, that is the military technical manual. I believe the torque in the manual was is in the range of 30-80 ft lb for the barrel nut.

Below I linked a how to from Midway discussing upper assembly.

http://www.midwayusa.com/general.mvc/index/how-to-build-ar-15-rifle

The last barrel I put on ended up being around 50 ft lbs. It took that much to get to a gas tube hole. Sneak up on the gas tube hole. Don't pass it up then back off the nut a little. This has potential to cause the barrel extension lug to rotate back as well due to clearance between the alignment dowel and the upper alignment groove. If you pass up the gas tube groove you want, back it off a fair amount and sneak up on it again.

I learned this the hard way and caused a slight misalignment and interference between my bolt and lugs in the extension.

[Tedward]

Good advice, I had been using a gas tube as my alignment tool. Just looking at Brownells and saw the barrel nut alignment tool. Now that is a good way to double check the alignment for your gas tube to bolt carrier gas key. Can't beat it for 5 bucks.

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/barrel-tools/barrel-nut-alignment-gauge-prod26480.aspx

[A.D.D. AR]

Keystone- I have used 55 inch/lbs before with a clamp on gas block, using one of those wheeler in/lb wrenches. Can't recall where I got that info, but that's what I did.
-mike

[aclark]

I just installed my Lilja last night and when I torqued it to 30ft/lbs it was almost exactly between 2 holes. I think I ended up somewhere around 50 ft/lbs to get it to the next hole. It was a pain in the ass because I thought my vice was going to pull off my MDF workbench top. Lesson learned, a solid wood top is in my future.

[LRRPF52]

If you guys use grease, tighten, then back off, tighten again, you will have better results aligning the teeth on an AR15 barrel nut. Minimum torque for a 5.56 NATO is 35 foot pounds. Armorer manual says 35-80ft lbs, but many experienced smiths will say you can exceed 80ft-lbs no problem on a 7075 T6 Type III hard coat aluminum upper.

I have a box of broken uppers given to me by people that were using the Panther Claw insert. I have always used the clamshell, but you can also clamp the barrel with circular vice inserts, apply gripping compound so the barrel won't spin, and torque the nut that way.

Then there is the reaction rod method.

[Keep The Change]

I use a tool that attaches to upper assembly lugs with pivot pins. Then there is a top piece that slides onto the picatinny flat top. I then clamp it in a vice side ways. It worked out really well. I think a guy makes them on ebay or AR-15. Good fit and worked great.

[WildBill3/75]

If you guys use grease, tighten, then back off, tighten again, you will have better results aligning the teeth on an AR15 barrel nut. Minimum torque for a 5.56 NATO is 35 foot pounds. Armorer manual says 35-80ft lbs, but many experienced smiths will say you can exceed 80ft-lbs no problem on a 7075 T6 Type III hard coat aluminum upper.

I have a box of broken uppers given to me by people that were using the Panther Claw insert. I have always used the clamshell, but you can also clamp the barrel with circular vice inserts, apply gripping compound so the barrel won't spin, and torque the nut that way.


Then there is the reaction rod method.

I agree that clamshell types are the best way to go. The panther claw in conjunction with the delrin flat top upper slide on piece looks the best imo.


With this said I've had no issue using a dpms panther claw putting barrels on/off uppers... I had to use around 100Ft lbs to remove the PF installed barrel on my mono and didn't damage it. The guys with the broken uppers must have had some low quality uppers and/or didn't support the upper when they were cranking with the wrench.

I also use the grease tight/untighten/tighten method using white lithium grease.

[LRRPF52]

If torque is being applied to the pivot pin and take down pin lugs laterally, they can crack. It even happened to a large frame .308 in the TD pin lug. The gun went full auto while a chick was shooting it her first time, then shotgunned during firing. The company blamed the owner, who didn't even own tools to work on it, and had sent it to them for repair after initial issues. The rear lug was cracked.

I know several builders that use the inserts with cross pins and have no issues, but then all of a sudden, one will crack if someone else gets on their tools and uses them.

[wheelguner]

AR15 Torque Value Chart*

-Carrier Key Screws: 50-58 in/lbs

-Barrel Nut: 30-80 ft/lbs

-Receiver Extension (Rifle): 35-39 ft/lbs

-Receiver Extension Castle Nut (Carbine): 38-42 ft/lbs

* Torques are from the current Army TM 9-1005-319-23&P W/C #8.

This came from this site:

http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES

[keystone183]

^^^This. Thank you very much!

[aclark]

This is the vice block to mount the upper in, very secure.

http://www.cabelas.com/product/Wheeler174-Delta-AR-15-Upper-Vise-Block-Clamp/1383269.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch.cmd%3Fform_state%3DsearchForm%26N%3D0%26fsch%3Dtrue%26Ntk%3DAllProducts%26Ntt%3Dar%2Bupper%2Breceiver%2Bblock%26WTz_l%3DHeader%253BSearch-All%2BProducts&Ntt=ar+upper+receiver+block&WTz_l=Header%3BSearch-All+Products

Used white lithium grease and tightened and backed off 3x times, each time the nut ended up in roughly the same spot. Just took some brute force to get it tightened down. I think my biggest issue was the cheap work bench.

[Lonehill]

AR15 Torque Value Chart*

-Carrier Key Screws: 50-58 in/lbs

-Barrel Nut: 30-80 ft/lbs

-Receiver Extension (Rifle): 35-39 ft/lbs

-Receiver Extension Castle Nut (Carbine): 38-42 ft/lbs

* Torques are from the current Army TM 9-1005-319-23&P W/C #8.

This came from this site:
http://www.weaponevolution.com/forum...AND-PROCEDURES

Just installed a Shilen HBAR barrel into a billet Mega receiver, VERY tight fit by the way. Set torque wrench to 30 ft lbs and tightened then loosened the Mil-spec barrel nut three times. The gas tube was almost perfectly aligned but not quite so I stepped up the torque and tightened a final time. The gas tube lined up perfect at a torque setting of only 32 lbs. Is this tight enough or should I try to advance the barrel nut 1 more hole (1/20th of a revolution)? Any thoughts? Thanks