Well,
It looks like it was either bad primers or mislabeled primers.
Opened a different case (1k) of CCI 500's and all seems well.

No more Failures. Loaded 10 more from the first "suspect" case and failure after failure again. The ones that fail in the 638, 642 and 442 will ignite in my Ruger SP101 and S&W 686.


My best guess is maybe Small Rifle or Small Pistol Magnums have been mislabeled.



In any case, I appreciate all the info and suggestions. I'll label these "suspect" and use them in the Henry or one of the two magnums.

I'm just glad to have my 638 back on board the boat and back to normal.