Variability in COL?

[Perplexed]

Your best bet is to go online with the manufacturers guidance or get one of their reloading manuals that can guide you for a low power shot shell recipe.
Some of the cowboy shooting forums should give some good intel as well.

I found some such intel, and loaded up some more shells with a lower-power recipe. Haven’t tried them yet, but I’m confident they’ll work. Thanks.