Last week I ask what to torque a barrel nut to .My question this week is what happens if you can't make it to the next gas tube hole beccause its too many ft lbs and the one before it is at only 40 ft lbs?
You could try to torque, break torque, and repeat until you have seated the torque four times; if the gas tube hole and notches don't line up after that, then you can use a fine sandpaper and a flat surface to take a VERY small amount of material off of the mating surface of the stripped upper receiver. It won't take much - go slow and check often.