I think that if the file is sealed they, yes even the police will have a hard time getting your records. I suspect it was a Juvenile crime and in most States that file goes away. However in some States the Juvenile conviction can bar a person from owning a firearm, some Felony charges will follow you. Also in some States the Juvenile system can impose a sentence even if probation that can go until age 21, moving the Juvenile offense into the Adult “time period” past age 18.
I used to issue carry permits and can say the other post is correct, if they “must issue” then the burden is on them to prove you are not entitled to a carry or pistol ownership permit. I know that it is easy to turn people away, however when you make application the clock starts ticking. It depends on the language of the law, in my State I was very pro gun and would issue unless they were clearly prohibited. I also applied common sense an old sealed conviction, then military service, sound ok to me. Other jurisdictions were known to be tougher; guys at my club would tell me all the problems they were having.
So after all this from my experience as one that issued them (now retired LEO), I would make application make sure you have all the required stuff, check, and safety class. I would enclose a cover letter explaining the situation and telling them the State said you have no problems. In my case once application was made, I had to deal with it and had time requirements in the Law 30 days for residents, 60 days if you lived out of State in the past 10years.
Try that just turn it in, see what they do, then if they deny look at the appeal process. If the person has a boss and we all do, talk with them if you cannot work it out. Then a lawyer is expensive but it might just take a letter from a lawyer to get them moving.
others should know. when i was young and dumb i did foolish things with some foolish people. hung out ounce with them got into some trouble. my criminal file was sealed. joined the army got out went to work and 13yrs later applied for a hand gun only to find out my file was never sealed. got intouch with state police took a little over a week my file is now sealed. went back to my police department to get a purchase permit. this should only take one day but the police department says they need my sealed file now the state police do the check i was just wondering why do they need a sealed file. when they can just send the paper work to the state. please if anyone can explaine this to me or just give me your opinion that would be great thankx