Re: How much variance should I accept in my brass?
JustC, the weight of the cases are close enough. What you might want to consider is fireformed volume. This matters a lot more then difference in extractor groove dimension.
I measure my brass by filling one with a fine powder. Then dump into other cases. What I have found is that even though there are slight difference in weight, the volumes are essentially the same.
Case volume determines pressure or variations in pressure. This affects vel and spreads.
I also shoot the brass for group. Any brass that shows up as a flyer gets marked and reshot. If it remains a flyer, it gets pitched.
I have found that with the above culling techniques, I have gotten all types of brass to shoot very well. Of course, all are sized properly and bullets seated straight.
To me, brass weight does not matter...case volume does.