The 155mm rounds were rumored to be either 0.1 kt or 0.5 kt yield, and the 8"
ones "Dial-a-yield" with settings of 0.5 to 2 kt. Hiroshima was a 13 kt yield
bomb, the Nagasaki one estimated at 20 kt.
The one live "Atomic Annie" shot was 15 kt but was detonated at its perfect
burst height and was assessed as far more effective than was expected --
equivalent to about a 25 or 30 kt burst.