It isn't glum. It's called "expungement". It is difficult on purpose. It isn't enough that he's "paid his debt"-he has to show that he's turned his life around, that he works and contributes to society, and that he has made himself into an upstanding citizen, the kind to whom society would have no second thoughts to giving firearms,voting, and office-holding rights.
The process will vary from state to state, whether the felony was state or federal, and what the crime was in the first place. A lot of that information can be found online, and if he has a Legal Aid chapter in his area he can consult them after he has his basic info together. If he's still in touch with his parole officer, that might be a source of info too. He will need a lawyer who knows that area of the law, but he wants to do as much of the work himself as he can, so he'll know if it is feasible at this time, and to keep his legal costs down.
In very few cases, though, is "having served one's debt" enough.
good luck.