The standard AR10 barrel nut requires between 30 and 80 foot-pounds, with most specs indicating around 85 foot-pounds. However, it is important to note that this specification assumes that the barrel nut is timed properly.
What is Barrel Timing?
AR10 barrel nut must be timed properly because the gas tube has to go through the barrel nut and the delta assembly.
Referenced BRD Gun Works
To do this we highly recommend using the Midwest Industries Reaction Rod for AR10.
The Midwest Industries .308 Upper Receiver Rod, made from 4140 Ordinance grade steel and finished with black oxide for corrosion resistance, is a versatile and durable tool suitable for AR-10 and LR .308 owners.
It won't damage the exterior of the upper receiver and is great for removing stubborn barrel nuts or installing muzzle devices without harming the index pin. This upper receiver rod is compatible with both forged and billet LR .308 and AR-10 upper receivers, and can be used horizontally or vertically in a bench vise
Doing it this way avoids adding shear damage to the barrel index post or the upper receiver.
Some barrel nuts have a notch cut out for the gas tube to slip through, while others require proper timing for screw installation onto the barrel nut through the rail.
How to Measure Torque When Installing a Barrel Nut?
Use an adjustable torque wrench that clicks when reaching a set torque spec.
Learn More: Fix Loose AR15 Barrel Nut