I fear that a 1929 bomb would have been impossible , even with a very early second world war.
most people dont seem to realise the vast amount of resources necessary for the Manhatten project , for almost 4 years there were thousands of centrifuges (each containing significant amounts of silver ,for which thay had to dip into the federal reserve) and over 150,000 people worked day and night just to manufacture the two bombs dropped on japan.Tis only bieng possible to the ,vast latent industrial capability that had been freed up by the great depression. And that was with the benefits of a decade of intensive reasearch and well grounded theory , niether of which existed in 1929
The only way i can see this happening would involve a much earlier POD (ie. splitting the atom in the last quarter of the 19C) of some kind of time travel....
Possibly involving ninjas....
or a Mutant alarm cloack of some kind...
Sir Scott
-destroyer of worlds