You are correct in regard to 18 US Code 922 restricting felons from possessing firearms. However, as with many situations, there are sometimes exceptions to the rule.
In 18 US CODE CHAPTER 44 - 921 DEFINITIONS- (33) (B) (ii)
A person shall not be considered to have been convicted of such an offense for the purpose of this chapter if the conviction has been expunged or set aside, or is an offense for which the person has been pardoned or has had civil rights restored (if the law of the applicable jurisdiction provides for the loss of civil rights under such an offense) unless the pardon, expungement or restoration of civil rights expressly provides that the person may not ship, transport, possess or receive firearms.
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The US Supreme Court has established that the basis of a complete restoration of Civil Rights must include Voting, holding public office and sitting on juries and that there must be no firearm restrictions in regard to the restoration.
Keep in mind that any Civil Rights Restoration that takes place would most likely be only State convictions. Anyone convicted in a Federal Court has no current remedy for restoration as it must come from the jurisdiction in which you were convicted of, and there is no active process of restoration in Federal Court.
Restrictions of Firearm possession of someone with restored rights would then be regulated by the State. One example is that at one time Tennessee law allowed a convicted felon with restored rights the right to possess firearm, with the exception of handguns. Since, the felon was restricted by the State from handguns, federal law made it illegal to possess any firearm.
Tennessee recently changed their firearms laws, which now allows some non-violent felons to restore all rights with no restrictions. However, anyone convicted of violent felonies, drug convictions, stalking, mental defects, having restraining orders, renouncing citizenship and even driving while intoxicated would bar you from firearm possession.
However, each State has different procedures in restoring citizenship rights, therefore its prudent upon you to seek out legal advice from a qualified attorney in that State. Keep in mind that if this situation of needing a restoration of rights applies to you, seek a experienced attorney in the area of civil rights restoration. A probate attorney may not be completely knowledgeable of all federal and state laws regarding this particular area of law.