Whats the biggest aniamal youve killed with an airgun?

[Mr. 16 gauge]

In answer to your question: feral house cat at close range; he was in a Havahart trap. Gun in question was a Crosman 760.

As to taking deer with a .22 rimfire....illegal in most states, but not everywhere!; check your state regs....and it is illegal in my home state (MI).

As for shooting Canada geese with an airgun: highly illegal and a violation of Federal law.....doesn't matter when or where or the circumstances......Waterfowl are protected by Federal law, and the only legal means of 'taking' them is with a shotgun or bow....no single projectile firearms! (and that includes airguns).