Yes it is critical to have proper fitment with the barrel Extension and Receiver. If you don't want to spend the extra $60 for a oversized barrel extension, then use High Temp Red Loctite. If we are talking about a Precision Rig then don't Half Ass it! Polishe the Barrel extension to a mirror finish, true your Receiver Face (by a Professional) and Bed or Thermal Fit the Barrel, make sure to season the receiver theads and apply some Anti Seize, and lastly don't over torque the barrel nut, 50-65 FTLBs is ideal.I wonder how much effect our use of glue, and/or oversized extensions/tighter receivers has on the whole thing?
Some are nearly an interference fit, and the ones that are not almost universally get glued.