To do it properly you need to be sure to use anti-seize on the barrel extension threads, torque/loosen the barrel to 40 ft lbs 3 times, and finally, if barrel nut is not aligned to allow proper intallation of the gas tube, continue to tighten until it is. The half-ass (no offense) manner in which you did the job will probably work, but you may also find it difficult to remove the barrel in the future due to galvanic action, cold welding, and overtorquing it. Also, I wouldn't trust the barrel and bolt to headspace themselves. While that may be correct in a general sense, having seen what grenaded AR looks like I have no desire for such an event to occur right next to me face. Headspace gages are cheap insurance.