TIL that people think "black on black crime" has any meaning. I would have thought he wanted to talk about gang violence, which is probably #3 or #4 on the list of gun death causes, behind domestic violence and maybe accidents (with suicides eclipsing both of these).
That's an interesting point, so I did some digging. I'm using 2007 as the reference year, because I can't find any more up-to-date sources on domestic murder.
There were 18,361 total homicides in the US in 2007, 10,129 of which were committed with firearms.
There were 1,975 gang homicides in 2007, or ~10.8% of all homicides [1] I can't find anything contemporaneous, but a 1995 study said that 94%-96% of gang homicides used a firearm. Using the lower number, that would mean 1,857 of those were firearm homicides, or 18.3% of all firearm homicides.
There were 2,340 domestic murders in 2007 [2] (the header says female victims of domestic violence, but that stat is for both genders). [4] says that in 2002 54% of domestic violence homicides were carried out with a firearm, so that would be about 1,264 or ~12.4% of all firearm homicides.
Neither of those numbers is isolated to firearms; I couldn't find any studies specifically scoped to firearms. I also didn't dig very hard into how they get those numbers.
Estimates on accidental deaths put them at ~400 a year. [3]
CDC data for 2007 says there were ~17k suicides with firearms in 2007 (these aren't counted in the homicide numbers above).
Gang violence does seem like it has more firearm homicides than domestic violence, but not by a staggering margin, and it may have flipped since 2007.