Unknown projectile

Could be a solid shot anti tank round with a Tracer element in the base WW II era

What I find strange is the missing of rotating band or emplacement for it !

Rotating band can come off by the blast , or simply by rust through the years in the open

506th, what is the provenience of this round? Where was it found?It's obviously an armor piercing round, and I too am puzzled by the lack of a rotating band or some wort (or any sort of indentation for one). But -- in the mid 19th century, the change over from smooth bore cannons to rifled guns began. There were at least two that I seem to recall that used projections which fit into large grooves /"rifling" on the inside of the barrel. The roughly circular rust stain about half-ways between the base and the tip could perhaps the rusted remains of such. Also, it seems as if the mid 19th century began the switch to iron-clad ships, which -- of course -- led to the development of armor piercing rounds. Could this be an armor piercing round for a naval cannon?