Why black men? Are you going to tell me the same isn't true of white men being killed by white men?

Nope, white males are murdered by almost exclusively other white males as well, that is absolutely true, but at a much lower rate. There were 6,790 black males murdered and 4616 white males murdered in the US in 2017 (both of them almost exclusively murdered by other males of the same race; female murderers and interracial murders are fairly rare).

White males are about 37% (~117,000,000) of the population... Black males are about 6.5% (20,000,000) of the population (these are 2016 population estimates).

4616/117,00,000 = .00003945299 6790/20,000,000 = .0003395 .00003945299/.0003395 = 8.6

Black males are murdered by other black males at slightly less than 8.6 times the rate white males are murdered murder by white males. (I say slightly less accounting for the previously mentioned rare instances of female murderers and interracial murders.)