Chinese researchers claim to be able to disable US tanks with fast-moving ball

> They found that a solid sphere, weighing 20kg [...] at about four times the speed of sound [...] 25 megajoules.

For comparison, the projectile from a US M829 tank round [0] involves a spike with a mass of 4.6kg traveling at an (initial) speed of mach 4.59, or around 5.70 megajoules. The propellant and all the other stuff which stays behind brings that up to 18.6kg.

I assume this cannonball's dramatically higher projectile-mass is needed in order to make up for accuracy, so that a glancing hit still rattles everything enough to make a difference.

[0] https://en.wikipedia.org/wiki/M829

It's like a modern cannonball. They say a 20kg "solid sphere" traveling at 4x the speed of sound could disable a tank by exerting forces on bolts that connect the pieces together, but otherwise leaving the tank with the appearance of being mostly unharmed.

Chinese researchers can claim this, but realistically, the US is one of the only countries that has repeatedly deployed its current tanks in a war context. If you don't have experience with tanks in a war, you'll very quickly learn what matters.

It's made out of LK99?