Umai pepperoni 40% Loss in weight.Case hardened

[Jim]

It’s hard to say, but I would go 48 hours next time. Also, it is best to make sure that there isn’t much airflow in the fermentation space, otherwise the outside of the sausage will dry before it has a chance to ferment. That could be a cause of some case hardening. As for the meat, the blend you describe should produce good pepperoni.
In commercial operations they use all kinds of cheap meat to make pepperoni (beef cheeks, etc.)
How big was the grind size? Bigger grind size like 3/8 in would give you more even drying.
As you are finding out, making dry sausage is an art.