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
Our Flag does not fly because the wind blows against it,
It proudly waves because a soldier's dying breath blows upon it.
USAF Forward Air Controller, 5th Spl Forces,
An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73