The sealing of the record will not restore your rights to own a gun. Your only option is to apply for a pardon, either directly to the governor, or through a certificate of rehabilitation if you qualify. How old are you now?
Sealing your record won't protect your gun rights. You can seek a pardon, though they're really tough to get. The only option I could see was reducing the charge to a misdemeanor, but that isn't possible, I think, since you've sealed the record.