http://blogs.mprnews.org/newscut/2015/09/a-bb-gun-is-a-firearm-court-rules/Just came across this article from September of last year - Minnesota courts ruled a BB gun is a firearm. The man that was convicted of having the BB gun illegally argued that the definition of a firearm from the Webster dictionary, which is a "weapon from which a shot is discharged by gunpowder", does not include a BB gun since gunpowder is not used. However, a case from 1988, concluded that a gas-propelled BB gun was a firearm, stating "...defines “firearms” for purposes of game and fish laws as “any gun from which shot or a projectile is discharged by means of an explosive, gas, or compressed air.”
The court also said that they asked the State Legislature in 2006 to address the vague wording, but they have not. So the precedent stands, which is that a BB gun is a firearm. The man then argued that BB guns are toys and the the Minnesota court ruled that paintball guns, which are gas-propelled, are not firearms since they are toys. The court decided that paintball guns are not intended to cause bodily harm and that they cause pain the same way a snow ball may cause pain, but BB guns are designed to cause bodily harm.
So, if you own an airsoft gun - be careful.