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/

Since the white man landed on American shores

Nah, you'd hear a crack from the bullets sonic boom, then immediately you'd hear the whistling in reverse and pitched down, followed by the pop from the gun.

The Doppler effect explains why pitch is higher for, say, an ambulance heading towards you, but as you approach the speed of sound, the sound waves all bunch up together and you'd just hear a sharp blast.

Faster than that and the sound waves created have to catch up. At 2x SoS, it would be the same pitch in reverse. Faster than that and the pitch drops.

Have you tried touchgrassmaxxing?