Unfortunately, you are in a bad position in this matter. The advice that you received is correct; in a criminal proceeding only an order from a judge can have this firearm released. And regretfully that judge refused to order this firearm released. I am not surprised since judges, in general, are very reluctant to order the release of a firearm when it is connected to a drug charge, at any level or final disposition.
Hence, for you are at the end of the legal process. The only legal option you have is to appeal the decision of the judge not to release the firearm. Good luck on that! You would be better off going pissing into the wind and hope for no spray-back.
The NRA is right, the legal cost of contesting all of this far exceeds the value of the AK. I too suggest that you forget about it and just go buy yourself a new AK.
Notice! Historically, the New Orleans Police Department is notoriously inefficient and corrupt. The New Orleans judicial system is only slightly better. Post Hurricane Katrina criminal investigations exposed all of this!
I know this is a bite out of the shit sandwich; but, you need to write off the AK.