Torque wrench question

[Alpha5717]

On the AR receiver wrench (at least mine) is a half inch cut for the torque wrench. I need to torque the gas tube nut so that I can stake it. The problem is, most half inch torque wrenches aren't super accurate at the low end of the scale plus you're losing some accuracy in the reading since the torque wrench goes into a long AR receiver wrench. I could go with a 3/8ths torque wrench and an adapter to make it work with the AR receiver wrench. But, I don't know how accurate that would be.

Does anyone here know which torque wrench I should buy and the best way to do this job?

 

[Control for Smilers]

On the AR receiver wrench (at least mine) is a half inch cut for the torque wrench. I need to torque the gas tube nut so that I can stake it. The problem is, most half inch torque wrenches aren't super accurate at the low end of the scale plus you're losing some accuracy in the reading since the torque wrench goes into a long AR receiver wrench. I could go with a 3/8ths torque wrench and an adapter to make it work with the AR receiver wrench. But, I don't know how accurate that would be.

Does anyone here know which torque wrench I should buy and the best way to do this job?

castle nut?

 

[Braxton1]

I will go out on a limb here and assume that he's talking about Carrier Keys (that's the only gas system item that gets torqued, other than Gas Block setscrews).

I use a 55 INCH-pound torque limiter from Fix-It Sticks. I've checked the calibration on them and they're pretty dog-gone accurate. You've just got to pray that you got Grade 8 screws as spec'ed, instead of pot metal stuff from Elbonia.

 

[rockyfatcat]

The 1/2 / 3/8 adapter will not affect the accuracy of your torque. Torque wrenches are most accurate in the middle of the torque range. If you are using any sort of crows foot, make sure it is 90 degrees to the wrench so you don’t add or subtract from the forces.

 

[BigMike]

Yes, you should be fine. A better wrench would give better low end accuracy, or you could just run an old school wrench that deflects with a needle whilst being torqued.

Just for info. Knights runs a castle-nut that holds a flared gas tube to the gas block. Seals it up tight.

 

[Alpha5717]

That is what happens when you are half asleep and still typing... My problem is torquing the buffer tube. Should I go with a 3 /8ths torque wrench and adapter to fit the receiver wrench OR a 1/ 2 inch torque wrench? Sorry for the brain fart.

And since this is the only use I have for a torque wrench, what brand (other than Harbor Freight) would you recommend?

 

[rockyfatcat]

Amazon.com

 

[User170512]

Calling in cmshoot

 

[jpm2953]

You are over thinking this. Give it a good snug, stake it(if you so chose) and forget about it.
If you aren’t mechanically inclined and don’t know what properly snugged is for this part, just take it somewhere. Don’t buy a torque wrench just for this

 

[cmshoot]

Torque spec for the castle nut is 38-42 foot/pounds. Set your wrench to 40ft/lbs and you’ll be fine, even if the wrench is off a little one way or the other.

I use a mix of Tekton and Snap-On foot/pound torque wrenches, and I use the Tekton the most.

I recommend a torque wrench because one person’s “snug” and another’s can be wildly different. I’ve had parts that folks put on “snugly” that I ended up having to apply Kroil and heat, and even cut off, to remove.

Get a wrench an do it correctly, or take it to someone that can.