Yes, it is a Centennial medal. It appears to be a white metal version of HK 32a. If so, it is the first I’ve seen in that alloy.

I don’t think it is listed in Rulau-Fuld, but it is a mule of the obverse of Baker 404 and the reverse of Baker 397. Holland incorrectly describes the obverse die in his number 38 by saying that the date in truncation under the bust is “1876,” when it is obviously 1776. Frossard describes the obverse correctly in his number 314, but neither author lists this particular mule. I do not own this medal in either bronze or white metal, but for illustration purposes I have included the obverse and reverse from the separate medals, below.

22.2 grams is spot on for a white metal version. That’s good for me because I knew of it only in bronze. My bronze pieces (different mules, same dies, weigh in at 26.5 to 32.0 grams. Kind of hard to expect a bronze piece to come in as low as 22.2, when my white metal pieces (again, same dies, different mules) range from 18.2 to 22.2 grams.