Very informative thanks. Would you please elaborate on tumbling contributing to brass hardening.
Brass is opposite steel (basically) when it comes to hardening. Heat hardens steel, heat softens brass.
When you "work" brass, it hardens, and the harder it gets the more brittle it gets as well as less accurate it becomes for the purpose of ammunition.
Stretch it (firing the ammo) compress it (resizing the case) and peening it (impacting it) [they rattle together in a vibratory tumbler] all hardens it.
A handloader seeking even moderate levels of accuracy should anneal the cases at least every fourth firing, if not on 2-3 firings.
Enjoy,
Tres
