How can you calculate the energy available from a projectile?

This question isn't so much that you know when it has left, the size of the bullet, how much "explosive" and where it came from but rather... let's assume that you have some kind of a very fast tracking radar system (fast updating) so that it can track the trajectory of the bullet, how can you figure out how much energy will be available from the momentum of this bullet?

I believe that currently there isn't a way to interact with a moving object (without touching it) in order to extract energy from it, but let's assume that you could.

Could you get an energy reading like in MeV's or Joules (I'm sorry to get my units wrong but I think it may get the point across better) from a bullet in the air?

I am aware that the "input force" occurs only once from a bullet, besides the acceleration due to the Earth's gravitational field.

I thought I would start with figuring out something like mass, current height, Earth's gravitational pull (32.2 ft/s/s) and also velocity of the bullet, perhaps air density...

I'd appreciate any ideas