I don't know about US law, does the court order specifically state gun or firearm? They are not necessarily the same animal. If it states firearm you may be able to own an airgun, if it states gun, then you're probably not allowed either. In the UK, there are laws relating to firearms and and less stringent laws relating to airguns. I would guess that similar laws exist in the US. To resolve this you would really need to see a solicitor.