As the buster rules might tell you, the damage formulas for buster damage have changed... in a good way!
Normal Attack - 1 Action - No Element or Subtype bonuses :: (Attack + Rapid) x 5
Full Charge Attack - 3 Actions - Element and Subtype bonuses, if they apply :: (Attack + Charge) x 20
To spare your poor soul the math, a starting buster with 1/1/1 stats does 10 damage with a normal shot, and 40 damage with a charged shot. Each applicable PowerUP boosts the damage of the normal shot by 5, and the charged shot by 20. As it was originally, a maxed 5/5/5 buster deals 50 damage on a normal shot and 200 on a charged shot.
Bonus!
Half Charge Attack - 2 Actions - Element and Subtype bonuses, if they apply :: (Attack + Charge) x 10
Now you can net all the bonuses from a charged shot in only 2 actions! As the name would indicate, it deals exactly half the damage of a full charged shot, but with less charge time. Minimum damage is 20 with a 1/1/1 buster, max is 100 with a 5/5/5 buster, and a relevant PowerUP boosts the damage of a half charged shot by 10.
Double bonus!
Because no one did it sooner, Pull Shot is now available as a buster effect upgrade in the Navi Shop. Cost is 1000z, same as Knockback Shot.