The effects from a Davy Crockett round would be expected to be similar to the effects from a backpack nuke or a terrorist-built weapon that fails to function properly.

Next slide is a video of a real world example.

7 July 1962 live-fire test of the Davy Crockett small nuclear weapon.

Davy Crockett video and following pictures taken from THE U.S. ARMY PRESENTS MF20 9811, IVY FLATS FILM REPORT, UNC 6/97

The yield from this device was less than one kiloton.

(equivalent to less than 1,000 tons of TNT)