Interesting! A few questions:
What level?
How common and advanced are firearms, and how easy is it to get reloads/powder? With pintle mounts I'm assuming it's more advanced than standard D&D pseudomedieval technology.
Aside from making the Orcs more Tolkienesque, any other nonstandard monsters/races in your gameworld?
Is the whole river wilderness, or are there some settled/"civilized" regions? (generally speaking, I know you don't want to give spoilers)

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