What will happen if the abuser tries to buy a gun when s/he isn't supposed to?
Before legally buying a gun, all buyers must undergo a criminal background check that is processed through the National Instant Criminal Background Check System (NICS). If the abuser falls into one of the categories that would make it illegal for him/her to own or possess a firearm under federal law, those records should be in the NICS and should appear when a background search is run. Therefore, the abuser should be prevented from buying a gun. However, not all states have automated record keeping systems, making it more difficult to process the criminal background check, and some criminals and abusers do slip through the system.
Generally, it is not a good idea to assume that because the abuser was able to buy a gun, it is legal for him/her to have one. The criminal background check system is not foolproof.
If the abuser has purchased a gun and you believe that this was illegal, see Who do I notify if I think the abuser should not have a gun?