You are missing the point.
2 guns from Memphis, end up in the hands of 2 nutcases from California and Nevada, and they kill 2 cops in Nevada and wound 2 in DC....
Sorry, that is not a coincidence.
Believe me I know all about gun dealing. The likelihood of that being random coincidence is off the scale.
That is a very small number of guns that were misused. One individual buying the guns for his own use, not liking them (or needing cash, getting divorced, medical bills, etc.) then reselling them in private party sales to other residents of the state of TN could easilly account for those guns. This is highly likely as most people sell a gun or two here and there. It is also perfectly legal.