15 kilotons
Instant death radius 1.1 miles
It was good enough
And would still quake all but the most determined
And aside from the material being fairly difficult to procure
The bomb itself is not difficult to make for someone relatively skilled with metals and wiring and primary powders ...
Especially if they are less concerned over the survival of the deliverer or use the bomb stationary with a timer or remote trigger or just a very long fuse like mcveigh used
The complication is in the bomb which is sorta typical combustion barometric altitude trigger compilation
The hard part was all the buildup to how does cordite exploding and hence forcing two varyingly enriched sets of uranium rings into one another down a barrel make a Big Bang .....
I used to use the map below to show people that a hiroshima bomb dropped in seattle’s U-district wouldnt even break windows in downtown Seattle, And they are not that far from each other. It was kind of a revelation. Sure, nukes are a bad thing, but kinda like smoking, not really as dangerous as most people think. Of course, when you get into the stuff like the Tsar Bomba, you get into the territory that most people think of when they think of nuclear weapons.
https://nuclearsecrecy.com/nukemap/
The trigger timing is what I thought was the hard part. The parts have to arrive all at the same instant in order to set off the chain reaction. One of the designs, Fat Man, was an external sphere that needed to be driven into its core. That was the Nagasaki plutonium bomb. Hiroshima Little Boy was something like a uranium bullet going down a barrel slamming into a uranium target.
In the summer of 1945 my mom was an El Paso college student living with her aunt and uncle. One morning her uncle was up before dawn when the sky to the west lit up like the Sun had come up from the wrong direction.