1973 Kennedy Clipped Planchet?

This is a really neat coin! According to information that I obtained from the US Mint on this type of error, it occurs during the rolling/bonding process.
Ken Potter

This may be of help. Similar type though the effect is quite different.
Ken

The biggest tip off that this is genuine is the weakness of strike in the area of insufficient metal where a pileup of an outer layer of cupronickel fell away. At least that is the way the Mint explained it to me. There may also have been some damage to the planchet before being struck but it's hard to tell in the images and wouldn't matter anyway as it would be a part of the error. Nice find!
Ken Potter

In looking at the coin again I see it is circulated so I would not be surprised if there is a bit of PMD but the area that appears "scooped out" on the obverse is clearly a part of the error. This is a form of Defective Planchet error.
KP

Typing from the phone is sometimes but I do it all the same.

The fact that there's something distinctly like Blakesley Effect on the coin really steers you away from a postmint event. How would that happen less than 180 out, though? Pretty fascinating coin.

Blowingwind36,
I think what you are calling "damage at the rim" is where loosely bonded planchet metal fell away. In the scenario that I described for the 1977 dime, where you see the "valley", this was the case. On your coin, this could have occurred during blanking, upsetting, as it took a ride to the press, or after it was struck or at all four phases. Shown here is a 1981-P dime that the Mint examined for me in 1985 (or so). It was described by them as a dime struck on planchet rolled to proper thickness with a copper reverse. They explained that it was due to coolant being trapped between the copper core and outer layer of cupronickel during bonding. As the heat and pressure increased during the bonding process, the outer layer of clad (above or below the trapped coolant) burst leaving an area of exposed copper that was eventually rolled to proper thickness. Some of the clad layer was rolled into this blank which later fell away creating what appears to be a straight clip. The "clip" caused an ejection mishap and the coin was double struck. I won the Most Unusual Error Award for this one at CONECA's Errorama in 1986. I still own it. Not the most spectacular coin I own but one of my favorites. BTW, the Blaksley Effect described by others is indeed a key to your coin's authenticity. Now I dare you to find it on my coin!
Ken

Schroedinger's Clip. It has to be there, because it's a clip, but it's not.

Being picky, isn't the filleting of the reverse rim going into the second strike indicative of Blakesley, or is that an artifact of the second strike?

Yes, now let's convince some of the moderators and site owner to hire a developer to make a mobile app. It's about time!! Other coin sites have them.

If not, we could find a member of ours to do it for us, and then pay him in coins. Hey, just a thought