51d Lincoln

Could be broadstruck, but something doesn't look quite right. This is a good question for Mike Diamond.

EDIT - Get it off the tube and take some pics perpendicular to the coin. It's hard to tell with those angled pictures.

Interesting. The strike is not distorted at all, nor does it look machined in any way. If you happened to have a pair of calipers with which to measure thickness, I'm guessing you'll find the thickness to be way low in the center of the depressed areas, or way high at the outside. I think there was a big pocket of air in the center of the planchet, and the strike mashed it away or forced it to the outsides of the coin when struck. Doesn't look like the collar was present for duty at the time, either.

here's the updated pics...taken with better lighting from directly overhead.
the coin is also slightly concave on the obverse side, resulting in an equal convex shape on the reverse. the coin does not rest lay flat as evidenced when sandwiched between two other cents. it also appears to be slightly thinner along the rim, but no wider in diameter.