What is This?

I found this in the desert.
approx. .575 ca. 21/2 inch long with 2" of lead. I’ve never seen anything like it
Thanks

Looks like the projectile form a 14.5mm FAT artillery trainer.

Some variants:
http://www.municion.org/14_5x51/14_5x51.htm

So, Will this thing explode?

The one depicted has already set off it’s spotting charge. So the answer is: no!

Whew, Thanks for the the info. Very ,much appreciated.