warm gun の意味は？

this site would tell you about this song and meaning of the lyrics through this host's consideration.
:Happiness Is A Warm Gun (song) - The Paul McCartney Project.
https://www.the-paulmccartney-project.com/song/happiness-is-a-warm-gun/
if you want to know more about it precisely, please comment your question to this site.
:THE BEATLES MINUTE: "Happiness Is A Warm Gun"
https://www.aaronkrerowicz.com/beatles-blog/the-beatles-minute-happiness-is-a-warm-gun