When a traumatised Vietnam vet escapes arrest in a small town and takes to the hills, he must use all of his combat skills to evade a sadistic sheriff and his deputies.

When a highly decorated Vietnam veteran is unjustly arrested and abused by a sadistic sheriff, he escapes and flees to the wilderness where he must use his survival skills to fight off the pursuing officers.
(35 words)

First Blood (1982)

I phrased the logline to spotlight the topical issue around the time of the movie's release, how Vietnam vets didn't get the respect and appreciation ?they felt they deserved for fighting a foolish war for a lost cause. ?Particularly since it was not a war of their own choosing -- they were drafted, military service being compulsory at the time.

That's the emotional core the movie tapped into, that created the Rambo film franchise.

If memory serves, it's after they arrest him and bring him in for questioning that he runs away. They abuse him and ask why he's carrying such a large knife - it's for hunting, etc...

So I think it's? the police abuse of power that was the inciting incident which triggered the monster to awaken.

After a PTSD suffering Vietnam vet is arrested by a small town sheriff, he must flee into the mountains and use his special forces skills to fight off the officers in pursuit.

What about:

"When a wandering Vietnam vet is harraded by a small-town sadistic sheriff,?he takes to the hills and must use all of his combat skills to evade him and his deputies"

Why? Why must? he evade them? You give no reason to root for the veteran. He escaped from arrest, seemingly for doing something wrong, and he continues to evade it.
Was he framed? Do they think he's crazy and don't believe he didn't do it?
What is his goal? To clear his name? To reach his girlfriend and then escape the town?