Overall I thought it was good. The dialogue can be tightened up. It reads more like talking heads. Many of the exchanges are too long. Imagine shooting this, you'll be focused on the person for a significant portion of time. While I'm not saying reduce everything to two lines, do go through and sift it down to what's essential.
Code:
GREG
Not just my savagery, I mean. All men like me. Violent
criminals keep society in order. More than the cops do,
anyway. Violence is a distraction, an excitement. It
gathers people’s attention. Every morning people are
eager to read in their newspapers about what sorts
of bad things men like me did the night before. People
are always in the mood for violence. Take this baseball
bat, for instance. I must of cracked three dozen heads
with it, but it’s always new. It’s fun, it’s fresh, it’s exciting.
Busting someone’s brains out will never lose my interest,
or that of the public.
JACK
You got a point here, or are you just trying to convince
me that everyone is violently insane?
This can be better broken up and condensed with the same overall message.
Code:
GREG
Not just mine. All men like me. Violent criminals keep
society in order. More than the cops do, anyway.
For the public, violence is a distraction, an excitement.
Every morning people are eager to read in their
newspapers about what sorts of bad things men like
me did the night before. People are always in the mood
for violence.
Greg takes the baseball bat and weighs it, tapping it in his
palm, staring at it.
GREG
Take this, for instance. I must of cracked three dozen heads
with it, but it’s always new. It’s fun, fresh, exciting. Busting
someone’s brains out will never lose my interest,
Greg looks up and holds it out in front of Jack's face.
GREG
... or that of the public.
JACK
You got a point here, or are you just trying to convince
me that everyone is violently insane?
By breaking it up, it becomes more readable and there are now useable shots. It's no longer just a close up flipping between two heads. The reader can start to see a medium shot of how Greg is acting. This is helpful for Greg's actor also. I removed just a few words to keep the same sense. Really, think about the poor actor who needs to deliver these lines.
The ending is unfulfilling because it doesn't bring the resolution you want. I'd change it a bit. Below is your original. Your actions are compact. That's fine for a story, but in a screenplay you want to break them out a bit more. That's true for the rest of your script, but I'll focus here on the last piece.
Code:
Both men reel backwards and Greg drops the gun. They stare
at their wounds. Greg pulls at the handle in his stomach. He
vomits blood.
GREG
Fuck. Fuck.
JACK
(examining his wound)
You son of a bitch!
Jack grabs the gun from the floor and fires three shots into
Greg’s torso. Greg collapses and begins to gurgle blood.
Jack begins to kick and stomp him.
JACK
Motherfucking son of a bitch!
Jack kneels down and pulls the handle out of Greg’s stomach.
Jack stabs Greg repeatedly with it. Greg grabs the revolver
and fires the final shot into Jack’s chest. Jack falls
backwards. Greg dies. Jack pukes blood as he pulls back
against a wall and leans on it. He breathes heavily.
You need to break up these action shots. It will lengthen your script slightly but it will give you a more realistic view of the timing.
Code:
Both men reel backwards and Greg drops the gun.
They stare at their wounds.
Greg pulls at the handle in his stomach. He vomits blood.
GREG
Fuck. Fuck.
JACK
You son of a bitch!
Jack grabs the gun from the floor and fires three shots into
Greg’s torso.
Greg collapses and begins to gurgle blood.
Jack stumbles towards him and begins to kick and stomp him.
JACK
Motherfucking son of a bitch!
Jack kneels down and pulls the handle out of Greg’s stomach.
Greg grabs the revolver and fires the final shot into Jack’s chest.
Jack falls backwards.
GREG
Are we so different, Jack?
Greg dies.
Jack pukes blood as he pulls back against a wall and leans on it. He breathes heavily.
He slowly slides down the wall leaving a smear of blood as he gazes over a Greg's
body.
It just needs something to tie it all together. The elements are broken out into shots.
Overall I think it is good for a short.