Little boy is basically a rilfle barrel
Cordite at top fired by ignited by primer set off by barometric device and Archie radar
Blows I think less enriched uranium down barrel, into more enriched or vice versa causing nuke explosion
Simpler than I would have figured
Yeah it looks real simple compared to Fat Man. Looks like both the “bullet” and the target were U-235 according to wiki. Thin Man was “inefficient” wasting unexploded U-235 I guess. The two bombs were named for Hammett pulp fiction, The Thin Man stories and Fat Man after a character in The Maltese Falcon.