Here's a great video for the OP to watch.
Bestill Creations thoughts part 3 - YouTube
I weigh but, I've done it since BH first hit the market over a decade ago. For most shooters and hunters, its not necessary. Those who weigh the charges are looking for more than average accuracy. Weighing provides the highest degree of consistency for the charge only. There are other contributing factors associated with extreme accuracy. Loading force, seating pressure, etc. Nothing is written in stone and the best shooters still have unanswered questions.
If one doesn't compete or isn't extremely serious, weighing is not necessary. I'd have no issues what so ever hunting to 200yds and my charges be by volume only. Things will change and as some have already mentioned, lot numbers change and so will the weight. They mentioned to measure out 10 VOLUME measurements and weigh them. Average the weight and use that charge for THAT LOT NUMBER ONLY. If you change lot numbers, repeat the process. This IMO is the very BEST METHOD. Shooters not using that method can very well be shorting themselves on velocity if they go by weight only. OMG... someone will go off on that
Example only........ Lot #32.... you measure out ten 120gr volume charges and weigh each, then average it. The average weight could be......... 82grs. That's 2grs under the 84gr max.
Lot #39.......... use the same process as above to get an average. The average weight of ten 120gr charges of Lot #39 is 96grs. That's an additional 12grs over the guys that are using 84grs. Remember....................... Western has always recommended the use of volume.
Some of us will be shooting a match this weekend at ranges of 800, 900 and 1,000yds. Every one of us will use the above mentioned Best Method.