Originally Posted by
coldblue
Long story short, I had occasion once to simply file a new slot for the gas tube where the desired toque was indicated. A chainsaw file worked well for this. The gas tube should not bare on any portion of the barrel nut in the first place. The gas tube slots are simply for tool engagement, and loosing two slots at 12 o'clock will not hinder the proper use of most 3-pin wrenches by selecting/engaging three other opposing slots. The hole the gas tube passes through in the upper receiver provides all the alignment necessary.