The AT4, Panzerfaust 3, Panzerfaust (WWII), and M72 LAW all have an instant reload time and they "Disappear" (sometimes come back for some reason)

They are one shot launchers, so the dissapearing is the player dropping the empty launcher. Sometimes they come back because you pick them up again

Not sure whether to keep this for realism or make it simpler to avoid confusion

The bad thing with the launchers dropping is when you pick them back up, you insta reload them, and fire. If you repeat that process, you can send out atleast 1 rocket per second...