From your first link: "Inside EXACTO bullets are optical guidance systems, aero-actuation controls, and multiple sensors"

Of course that could all be a lie to throw adversaries off the scent, but the trouble with trying to keep a bullet top-secret is the moment you use it, the enemy has as many as they want to study...

Could it contain a charge or instability that destroys the useful innovations when it strikes the target, to prevent that? Even regular bullets look deformed when they hit something, it seems like if you want to slow down enemy research you could exploit that

> Some people are assuming it has fins, but none are visible in diagrams.

Many years ago I saw a concept of a guided machine gun bullet in a "scientific" magazine; the concept involved steering by a mechanism that moved a lump of mass within the bullet around.

How in the world does that work? Bullets spin at ridiculous rates; some 3000 RPS. At long distances it'll have made over 10k revolutions before it hits the target!

I honestly don't know. I vaguely remember a schematic I saw some 10-15 years ago or so. It may very well not work at all, it was a concept.