Quick question for an experienced AR builder

[BamaFan]

I have a 9mm AR and am replacing the hand guard. The new one came with a barrel nut that is round but that has a faceted section for a wrench (like a crescent wrench, not barrel nut wrench). Old barrel nut comes off easily and new one will screw right on. Do I have to use a torque wrench on the barrel nut or am I safe to just tighten it up? Also, when I removed the barrel it was very oily (the part that slides into the upper) - should it be?

 

[Allsmiles]

Normal torque is 30-80lbs on barrel nuts. Make sure to grease threads so they don't gall putting new nut on. Yes, there should be some oil/grease on barrel extention

 

[BamaFan]

Normal torque is 30-80lbs on barrel nuts. Make sure to grease threads so they don't gall putting new nut on. Yes, there should be some oil/grease on barrel extention

Thanks. That's a pretty big range on the torque. Is a torque wrench imperative (and does the fact that it's 9mm change the answer)?

 

[Wallace's]

Barrel nut torque specs for non GI barrel nuts should be followed. Do not use the 30-80 TM values as the high side can destroy barrel nuts like what Geissele and other supply (aluminum vs steel). The type barrel nut you have should be torqued using a crows foot. If the barrel nut does not require indexing and has a torque range, I prefer the lighter side of the torque values personally. General though, non GI barrel nut torque values are generally in the 35-55 range. It’s important not to exceed the max as it can result in damage to the barrel nut threads and or barrel nut wrench surface.

Aeroshell 33ms, now known as 64 should be used to prevent galling. Also, be sure to follow any thread seasoning instructions as to make for a proper fit without galling of the threads or later loosening from heat/vibration and thread surfaces that have not been “mated/seasoned/slight” to each other.

 

[Wallace's]

Thanks. That's a pretty big range on the torque. Is a torque wrench imperative (and does the fact that it's 9mm change the answer)?

Caliber doesn’t matter. Each aftermarket barrel nut has its own torque value(s). The 30-80 range is for indexing for a gas tube on a DI Rifle. Since the GI barrel nut tines obscure the passthrough in the upper for the gas tube, the range is set as to allow it to lineup but still have limit values.

 

[Allsmiles]

I forgot to put grease on one a long time ago. Galling sucks to say the least.

 

[Plinker66]

Git yerself a barrel shim kit if yer gas tube won’t line up nice and tight.

https://www.brownells.com/rifle-par...re/washers/barrel-nut-shim-kit-prod96013.aspx