Free: Contests & Raffles.
For popping rabbits, none. They're illegal for hunting in Washington.
Page 64 in the Big Game Pamphlet.11. Prohibited firearms/hunting methodsIt is illegal to:• Hunt game birds with a shotgun capableof holding more than three shells.• Hunt game birds with a rifle or pistol,except forest grouse.• Hunt game birds or game animals withanything other than a firearm, a bow andarrow, or by falconry. Bullfrogs may onlybe taken by angling, hand dip netting,gigging, and bow and arrow.Pellet guns are not considered firearms per WAC 9.41.010http://apps.leg.wa.gov/RCW/default.aspx?cite=9.41.010"(1) "Firearm" means a weapon or device from which a projectile or projectiles may be fired by an explosive such as gunpowder."