The Harrington & Richardson Special Purpose Individual Weapon (SPIW) prototype rifle designed to fire triple-bore "trounds" with three saboted flechettes.
https://s3-us-west-1.amazonaws.com/h...rdson_spiw.jpg
Previously:
https://www.homemadetools.net/forum/...933#post148789
https://www.homemadetools.net/forum/...9554#post89546
https://www.homemadetools.net/forum/...612#post123362
https://www.homemadetools.net/forum/...341#post135208