There are many valid criticism of US, but this one is a total BS.

Even if we ignore that it is impossible to make bullet play an anthem (how would it play in a fraction of second? Or how they could make it play multiple notes one after another?) Kel Tec doesn't even make bullets.

This is made by CompBullet, supposedly makes the bullet faster with lower recoil. The company isn't even American it is Italian: https://bulletin.accurateshooter.com/2011/12/from-italy-with-holes-the-radical-ported-compbullet/