I have found that sometimes Hickory chips can be a little strong (sometimes). As a "green/free" alternative, I pickup the husks from Shag Bark Hickory trees. The husks are up to 1/4" thick.
I found this out by accident when we were camping at a local campground near Mohican State Park in Ohio. I wanted something to grill with and had left the chips at home. The property has a large stand of Shag Bark Hickory trees and the nuts had been falling (it was fall of course). I picked the green husks up, left the nuts for the squirrels. I mashed them up with a hammer, soaked in water an bit and used them just as I would have used Hickory wood chips.
They provided a nice, mild Hickory flavor, were free and don't harm the trees to use. I pick them up in the fall and stick them in the freezer (seems to help with preventing them from drying out too much).
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