Re: culling brass
Think it depends on what level of accuracy you are expecting?
Some 1k BR guys sort to .1, most go to .5, some do not sort at all but they are rare. I subscribe to the .5 gr school if it is all over the place. However If I have less than 1% variance except ends of extreme spreads, I throw the ends of the bell curve out and use the whole lot. Lot of discussion as to what you are weighing anyway, ie wall thickness, case head etc.
Others take weighed brass normally within 1 gr in lots of 20 then shot over chrono and mark brass by uniformity of MV as whether record or sighter round.
If for hunting gun use 1% or one grain and just shoot it.