Subverted: The shot seems to kill Mac but he comes back a scene later...
Double Subverted: ... to die from a second bullet.
The gun shop Bill frequents is advertising the Super Bullet, which is guaranteed to drop your opponents even if it just grazes them.
Just being shot at is enough to scare Mooks to death, even if the bullets come nowhere near them.
Zig Zagged: Bill shoots Mac, who appears to die instantly. Then, as Bill turns to walk away, Mac opens his eyes, crawls forward, and shoots Bil... who dies instantly.
Averted: Mac gets shot and lives long enough to bleed out and deliver a Final Speech.
Enforced: The producers of this film are big on gun control and want to reinforce how deadly guns can be.
Lampshaded: “This gun shoots death!”
Invoked: Bill practices shooting for the vitals for clean kills.
Defied: Bill practices to avoid shooting the vitals.
Discussed: "Well, I guess one shot is all it takes..."
Conversed: "Wow, he died rather quickly, considering I shot him in the foot..."
Deconstructed: Any world in which bullets are so lethal is a world in which professionals who often face gunfights are bitter and cynical, leading to a swathe of Sociopathic Hero tendencies. You could die at any moment without even knowing what killed you. Such situations provoke fatalistic attitudes.