1906 IHC ANACS MS60 RB "Weak Strike"?

Very interesting!

Very interesting coin.

Other causes could include improperly spaced dies, an improperly prepared or annealed planchet, die failure (but both dies at once?), or low striking pressure. The lower relief portions of the dies seem adequately struck, so improper die pressure is my guess.

The concept of an adjustment strike is hotly debated.

Years ago, I saw a series of 1964-D Kennedy half dollars displayed at a coin show in a Capitol Plastics holder. The dealer described them as "set-up strikes," and there was a clear progression from weaker to stronger strikes (or from stronger to weaker strikes). I have no idea whether they were from the same die pair, were in fact a progression (or regression), or were the result of strike pressure. I just know what the dealer described them as and how they appeared to the eye.

My hunch is that in more recent years, an intentional press set-up / adjustment strike would have been destroyed, rather than allowed to be placed in circulation. As for coins struck more than a century ago, I have no idea. By 1906, there wouldn't have been any doubt in Philadelphia as to the die spacing or strike pressure needed to strike a bronze cent UNLESS a new coining press (or type of press) was used. Finding that information would require a scavenger hunt through Philadelphia mint procurement records, accounts payable, shipping and receiving logs, and inventories.

Several possibilities exist. On a mechanical press, a power failure could allow a strike or two to occur before the press completely stops. On a hydraulic press, the same could occur with a loss of hydraulic pressure. "Could" doesn't imply "did."

I know this doesn't give a clear answer, but it's the best I can offer. Others may have much better thoughts on this coin.