I think practice and that word instinct.I used one off and on for years but was never good.Some kids and adults were unbelievable shots!
We had a Oiler in the Union Camp paper mill at Savannah Georgia who carried one and shot the rats as he traveled the mill oiling machinery.The man was unbelievable.You would have to see the shots he made to believe him.He hit running Rats regularly.He was even deadly on English Sparrows as small as they were.I worked in the millwright shop before transferring.We would throw the old Bearings in a drum.He would remove the balls from the ones he wanted to use for ammo.He said that he had shot one all of his life.
I knew quite a few kids who hunted with them in the 50's.They had no money for BB guns,22s,BBs or shells.I knew some who often killed *****,ducks,geese,squirrels and rabbits.They were good stalkers as well as shots.They did this year round and this was part of their families food supply.Many animals were considered pest then and no season on them.You could kill most birds year round.Robins and Blackbirds were prime eating and lawful outside of most town limits.
They also trapped with handmade traps and snares.I do not believe the Game Wardens tried very hard to catch the ones who did it because of hunger as long as they did not get greedy and start selling it.Now this is a personal opinion.
I love you Brothers and Sisters.peewee