dickgally83 welcome to CB. I appreciate your concerns and do put a cover over my smelting pot, not for rocks or live rounds (live rounds are extremely hard to miss) but in case I missed cutting a fully jacketed bullet.
In the berms I'm used to, one would be hard-pressed to pick up much lead without doing some digging. I think we'd all love to find berm like you mention. How many buckets did you fill getting that 300 pounds?
Why would one shake or pour their smelting pot? we either use dippers or have a bottom pour feature. Also when dealing with molten lead, most wear at least eye and hand protection if not long sleeves or leathers.