Firearms purchase rights taken away, or concealed pistol license taken away?

As a juvenile, I plead guilty to a 4th degree assault (non domestic) and part of the plea bargain either said that I give up my rights to purchase a firearm, or I give up my rights to purchase a concealed pistol permit. I can't recall which one it was. The prosecutor told me that if I wanted my rights restored, I'd have to go back to court as an adult. I'm 21 now, and I've had my record sealed. I've applied to purchase a handgun, and I was qualified. I was also qualified to purchase a concealed pistol permit as well.
I asked the police department about how my rights were taken away, and they said since my record is sealed, they can't access my record to see that info, however I've read that having your record sealed doesn't restore your rights, necessarily, so I'm a bit confused. How does having my record sealed not restore my rights, but the police said since my record is sealed, they can't see any prohibiters that would prevent me from getting the gun or permit?

If your record is sealed then they can't deny you your second amendment rights. Now you just have to stay clean so your record stays sealed. A 4th degree assault usually isn't enough to take away your rights though, but I suppose it depends on the state.