When you know a firearm's effective killing range, you can determine: which animals you can hunt which stance to use when shooting whether you are aiming at the target when a shot will give a clean kill?
The answer that best fits the question is that 'when a shot will give a clean kill' because a firearm's killing range can be known or considered to be more effective if it has the capacity of providing a clean kill with only using a one shot and does not require for a second or more.
