Prof Timothy Smith of the U of Minn. has a plan to at least help cover the costs of gun violence which he sees as quite reasonable. It's an annual registration fee on rifles and pistols amounting to $15/year on rifles and $200/yr on pistols. Presumably we would get little license plates to affix to our guns to which the year and month sticker would be attached.
Only a couple of problems.
Item 1 is that word "registration". It's been tried in Australia, Connecticut, New York, and Canada and the compliance rate varies from 5-20%. In less liberal areas I foresee lower rates.
Item 2 is that you're assessing a tax on an enumerated right, you know like voting. Of course if Hill gets elected the poll tax may see a revival and I'm sure her Supreme court will see nothing wrong with that.
My suggestion if you really want to reduce the number of gun deaths in this country would be to attack not the guns, but the users. Since the professor has no problem with a poll tax, let me suggest he switch his emphasis to the users and bring back the post civil war Black Codes. Most homicides are, alas committed by black and Hispanic youth against other black and Hispanic youth. making it illegal for blacks or Hispanics to own guns would no doubt reduce the firearm death rate by about 90%, excluding suicides.
Might be worth a government grant and certainly a couple of doctoral dissertations to gather up some grad students and visit the appropriate areas of Minneapolis-St Paul and try their hands at getting the high risk population to turn in their guns voluntarily.