There was a republican special counsel OR just a republican US Attorney left over from the previous administration who the DOJ tasked with investigating Hunter Biden. You know he had that laptop after all (riiiiiight) and was supposedly doing crazy things in Ukraine so that is why they "needed" to investigate Hunter.

After that investigation they met with Hunter and his attorney and worked out a plea deal for the charges that came out of the investigation. They went to court with a plea deal and while they were in court, the judge found something wrong with the pleading and it was overturned I believe because the way it was set up, the government could come back and recharge Hunter (or something like that). The US Attorney was instructed to go back and try again. I believe that is how the 2 cases against him came about. Funny, isn't it that the ONLY things they found to charge him with, after all of the shit they were saying about him, Burisma and his dad, were a tax charge and the gun charge. 

The gun charge is a bogus charge because it is not usually legally pursued. Yes, when you apply to buy a gun, or whatever you do when you get a gun, you sign something saying you are not under the influence of (& maybe not addicted to???) illegal drugs. Hunter applied for a gun permit and swore that he wasn't addicted to/on drugs and he was, so the (Republican) US Attorney decided to prosecute him for that. This is not usually a crime that people are charged with and if it was, there would be a ton more people in jail, I think.

So, like David said, it was a dirty tricks op, one of many they have tried to use against Biden and the Dems.