As for Blacks being responsible for a disproportionate amount of the violence reported in the crime stats - maybe, but they are also suffering a diproportionate amount of the poverty going around too. To draw the conclusions you come to, you'd have to examine the murder/violent crime rate of poor white americans and find it was lower than that of poor blacks.
Of course, that does NOT let blacks off the hook. They are at least partially responsible for the poverty that goes hand in hand with violence. At the least its not completely "whiteys" fault.