Firearms under 500fps and 5.7 joules are not subject to classification, they are what's commonly known as "uncontrolled firearms" and do not fall into any of the standard three categories (non-restricted, restricted or prohibited) regardless of action type, semi auto, full auto or barrel length. It should also be noted however, that replica firearms, defined as anything closely resembling a real firearm without actually being a firearm, are prohibited devices. In order to be a firearm it must meet the criminal code definition, a barrelled weapon capable of expelling projectiles with sufficient force to cause gross bodily injury or death. The common standard for gross bodily injury is penetration of the eye. As such, if your BB gun is capable of shooting someone's eye out, but does not shoot over 500FPS or 5.7joules it is neither a replica nor any form of controlled firearm. It is not subject to classification, there is no licencing requirement, or storage or transport regulations. That said, they are still considered weapons, so offences like carrying a concealed weapon still apply.