That can always be the case. Minor things like the tubes not lined up and tight, gas tube touching a bit, not mating the thread surfaces on the barrel nut/reciever, and so on. Just minor things that can make a difference and can add up. Or not if you have a super hummer tube sometimes.
Its one reason I cut away one "tit" on any kind of barrel nut, I don't want that gas tube rubbing. I can't prove it matters, but in my mind it matters.
