In the lobby of the old Carnarvon WA tracking station in the early 70's they had on display a small fuel tank that had survived re-entry.
From memory it was about 250 - 300 mm diameter and looked pretty much intact except that it was split about half way around, presumably damage from when it had hit the ground.
Not a bad effort considering that the shell thickness was probably (again from memory) only about 0.5 mm - total mass only about 0.6.kg.
Would I like to have been hit by that? No I would not.