Just discovered something neat

[Parzival]

While you have a pistol drawn quickly double tap R1 (RB for Xbox, I assume) and Arthur or John will spin it on his finger before holstering it.

[Anc1entC0re]

I found this out by accident months after having the game. I don't remember it being a feature throughout the entire first time I played the story though so I don't know if it was added in after as part of an update or I just didn't use the controls for it.