Lost state's CWP laws say something like the BG must have opportunity, intent, and ability.
It's the last that come into play. If someone is threatening to kill you with a knife from 50 feet away from you and isn't moving toward you, you can't shoot him. He doesn't have the ability to kill you with a knife from that distance.
As someone else said, most gunfights occur at very close range. I practice to shoot accurately and quickly at those ranges. 5 yards, 10 yards, and maybe once a month, 20 yards.