It's an easy fix if the threads aren't too F'd up.
Here's my recommendation:
If you stripped out the threads on either the screw or your action, DO NOT do this repair yourself. It's beyond your skill set.
If an action screw doesn't thread in easily, don't be ham fisted and force it.
Take the rifle to someone competent, and if you didn't damage the action, it'll be fixed in 5 minutes.