So what you're supposed to believe is that a gun confiscation that was over by 1997 was responsible for a long-term decline in homicides that did not start until 2002, which coincided with a sustained period of guns per capita returning toward pre-confiscation levels.
It went up, from 315, to 342.
A ten percent increase in homicides in the US is notable. The same in a population The size of the above falls within the realm of statistically significant.
You're really drawing conclusions the data doesn't support.
The gun buyback isn’t something you’d expect to have a delayed impact on homicides. Certain weapons were banned, they were confiscated, and the program was over by 1997. Those guns could not be used to kill people. The number of guns started to go back up right after, as well.
It seems weird to say U.S. dropped "more" with these numbers.