I load for .223 for my AR for over the course, Nat'l Match work...200, 300 & 600 yards.
For the short distances (200 and 300 yds), I cull my brass for obvious imperfections, both military and commercial, and I sort for head stamp, (and also year group for military) and trim to length. That's it.
For 600, however, add'l effort is worth it in terms of group size. I weigh my cases and sort the brass accordingly; I check the length and trim if necessary; then ream the primer hole and clean the pocket to ensure uniformity.
As to powder charges, I throw from a measure for all distances, checking for uniformity every ten rounds with a scale; and have proved to my satisfaction that weighing each charge makes no difference at any yardage.
For 600 yds, the add'l time spent sorting and weighing brass makes a difference. My groups are better with the add'l work, and they're more uniform as well, i.e. fewer un-called flyers.
If you want to see a complete treatise on load development and component selection for match level precision, read Zediker's, "Handloading for Competition". It's worth the price of the book, as is his, "The Competitive AR-15".
Best regards, Rod
Cherish our flag, honor it, defend what it stands for or get the hell out. Our Freedoms are not free, they've been paid for many times over by heros in uniform. Far better men than I, died that we could be FREE.
USAF FAC, 5th Spl Forces, An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73