1971- D Kennedy Half - Double Eye Lid!

Better obverse picture!

When a coin is struck under such hard and fast pressure the metal is forced to flow (think of the molecules being moved - which is what is happening) into the die's devices at a very fast rate. If we were one of those molecules, the forces all around us are not equal since various areas of the die details can accept more volume (deeper impressed devices on the final coin), or less. Therefore some molecules by us will be more rapidly flowing into the larger openening between the dies for deep er devices while other areas will become hardened as a bottle neck situation occurs with some molecules trying to fit into smaller cavities.

All this means different areas of the metal will be more prone to movement than others. So some of the softer areas will be more susceptible to the smearing of Machine Doubling if the dies are loose.

Granted - all of the above is just a hypothetical guess from someone who has taught physics - but not specifically concerning metallurgy. I am applying general physics theories to how material will react. Sometimes the physics of a specific material is changed under rapid high pressure conditions. Also, the heating up of the metal during this process may also dictate other properties I know nothing of.

I am putting this out as theory for correction by someone who knows more about metallurgy in minting coins.

Actually John Wexler was at the mint and he got to see a coin struck and they handed it to him. But he mentioned the coin was not hot at all. (which surprised him also) So heat has nothing to do with it. Kind of the like the saying. It wasn't the bust on the train tracks that damaged the bus, but the train that hit it. So after the coin was struck, on the way up from the coin, die movement damaged the fresh new devices. (The train that damaged the coin in this case)

There is sometimes more bounce after the strike that makes this happen almost field lever, sometimes half way up and other times touching the upper part of the devices. It all depends on the looseness of the machine. This can occur differently from strike to strike:

Note the markers are all the same. These coins were is the same OBW roll. Note they are different from strike to strike and sometimes repeating patterns on other examples I found in the roll. Note on these examples the push of the dies moved and like pushed snow, pushed upwards from the movement and push of the machine.