Im back in business, i got my garrett detector back from the factory yesterday,it was being fixed and it works great now. So i went out today on a trail that was built in the 1870's and found a few nails with the square tops and found a half a hoseshoe and the third thing i have no clue what it is. it pretty heavy, made of some kind of metal and has 817 stamped into it. If anyone can please tell me what it is that would be great. also can someone tell me the best way to clean rusty metal. thanks.