So. Guess what? Turns out that stone was ALREADY on the material list for squad weapons. Know what that means? I can zig-zag yet again because I'm a fucking derp, and set arrows to use faked stone again. Just need to ensure the arrow-only version doesn't populate the material lists with redundant entries.
EDIT: Scratch that, just adding the demanded token for stone ammo to stockpile messes with uniforms. >.<