The next question is what can you do about the weight variance and is it important? The only answer I can come up with is - nothing. And it must not be very important because no one seems concerned - at least for straight sided handgun cases.
That is pretty much the situation Steve. Now if you were doing some bench rest shooting with center fire rifles looking for itty bitty groups way down range then the consistency of your cases especially in case volume would make a difference. But as you determined, for straight wall pistol cases used in causal range plinking, no big deal. I normally don't sort my pistol brass in any manner.