Wet Tumbling

[Texas10]

Again, I believe this to be a chemical bonding, brass and copper are known to have this trait
.

Yes, thank you. I'd have to agree that it's chemical bonding, not really neck tension.

Perhaps that is why Federal coats the inside of the case neck with tar before seating the 50 gr. bullet in the 223 tipped varmint loads.

[Mozella]

According to metallurgy 101. the structure of any metal only changes with the introduction of heat and by cold working. ......... snip.........

In Metallurgy 201 you would learn about precipitation hardening which in some metals and in particular alloys occurs at room temperature without any cold working. This doesn't happen with cartridge brass and would not be worth mentioning were it not for the fact that this is the Internet where picking nits is the most popular sport. At any rate, precipitation hardening is a very common way to harden certain metals. Plus it's easy; you just let it sit there.