Originally Posted by Foxbat
For clarity, estocs were not meant for piercing plate armor, or even good quality riveted mail for the simple reason that they were not capable of doing that. They were capable of defeating leather armor, gambesons and low quality mail, but not much more than this.
Please provide your references ?
It is not the armor plate itself that is to be pierced but the small openings areas were the plate armor connects such as were the Paulerons, Vembrances, Rerebrace, Cuter, Tassets, etc. And yes a good Estoc will penetrate good mail. Chain mail primarily protects against cuts and slash but is vulnerable to trust, tightly connected mail rings(high quality) and lesser tightly connected rings(low quality). Thinner/ weaker blades such as the one shown here might break when driven between the Paulderons and breast plate.
Please see this very good definition of the Estoc again and its purpose again:
Its actually a good explanation made in short and clear.
Unfortunately I am traveling right now. So I can not show you photos of my own period armor's and chain mails and armor piercing and fighting weapons. Its a interesting subject in it self. Subject such as Estoc, armor piercing daggers, war hammers, pole arms, pole axes etc :-) The original items makes it easy to understand the connections regarding the aforementioned.
Hand and a half Estoc fighting during tournament. Note how the combatants are searching for the opening in the opponents plate armor