Gun purchase OK after domestic violence charge and conviction?

I doubt he will be able to buy one down at walmart because the fed and the NICS, but as an american citizen I believe he has every right to own a gun and I would never convict him. I think black powder is still ok even with the feds but I might have that wrong. They love that they can "ban" you from owning a gun even if you have done nothing illegal with a gun. This is a great way for them to take away guns. It is also unconstitutional.