Gun-grabbers are being routed as a judge’s ruling may upset a decades-old ban on popular sporting rifles. The decision Tuesday by U.S. District Judge Peter Sheridan was made using previous Supreme Court decisions as a guide. According to Reason, Sheridan approached two lawsuits challenging New Jersey’s ban on so-called assault weapons, considering the matters in one joint decision. Although New Jersey’s Assault Firearms Law mentioned a number of specific semi-automatic firearms, including shotguns and rifles, the judge only considered one popular type of weapon — the AR-15. Other weapons proh…