[Suicide Junkie]

My tests (with 20+ of each type of armor) have shown that it does not work that way.

Armor is targetted somewhat randomly. Lower hitpoint armor components are targetted much more often, but not always.
Damage proceeds normally. If there are multiple armors of different sizes, occasionally the tougher one may be hit but not destroyed, and the next shot will kill two or three of the smaller armors.

Internals are targetted in the opposite way. In general, it is close to "one lottery ticket per hitpoint" type of thing, although there is a tendency for stronger internal components to be hit more often than that.