Iron buckle, possible pipe, three ringer, and musket ball in civil war campsite

I found a hunted out civil war campsite but found a few finds. Any help to ID the buckle and other iron pieces as a civil war relic and what type of rifle and caliber the bullet is would be greatly appreciated. I think the one piece of iron looks kind of like a pipe bowl but it seems to be solid and not hollow (maybe corrosion filled the bowl?). Also what might be the source of the scratches running across the tip of the three ringer?

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