The Davy Crocket or to give it it's full name the M-29 Davy Crockett Weapon System was a recoiless rifle which the US army designed to fire a tactical nuclear projectile. Seriously read that again, they made an infantry weapon that fired a nuclear payload. This thing was essentially a grenade launcher that fired H-Bombs.
To quote Wikipedia:
It proved to have poor accuracy in testing, so the shell's greatest effect would have been its extreme radiation hazard. The M-388 would produce an almost instantly lethal radiation dosage (in excess of 10,000 rem) within 500 feet (150 m), and a probably fatal dose (around 600 rem) within a quarter mile (400 m).
They made over 2,000 of these things and it stayed in service until the 70s because the US military does not give a shit.