Start off at 10 yards, using a stable position, like prone.

Shoot a shot string at the target from 10 yds at the bull. Do not adjust your aim at no point.

Take up any adjustment on the scopes turrets to bring the pellets nearer to the bull.

Shoot another 5 shot string at the bull.
Repeat this until your shots are hitting the bull each time.

Move back to 25 yards and repeat a 5 shot string and make adjustments if necessary.

Only adjust after 5 shots as you could be chasing your tail all over the target card.