This episode is so stupid and wrongheaded it's annoying.
1) The weapon's penetration capabilities are simply ridiculous. The ability to readily penetrate stuff generally comes from the bullet jacketing (i.e., teflon). Muzzle velocity is only a part of it. Going through four walls (one concrete), a body, and
retaining instant kill capability at the end
after a long flight for a normally jacketed bullet is just preposterously unlikely.
2) The reverse trajectory problem is hardly complex. It's one of the most classic problems in mathematics -- one reason US artillery batteries are so dangerous is that they have computers that use radar to instantly recognize incoming rounds and respond to take out the location where the original round was fired from. Given the presupposed two-wall penetration at the end, you have a direct line of trajectory which provides a very narrow range of original sites. You can narrow that down further by studying the endpoint behavior to get an estimate of velocity as it passed through the end walls.
3) The whole anti-gun, anti-weapons-sale issue is argued as one-sided, which is blatantly incorrect (Typical -- the anti-gun people NEVER argue it fairly. Always one side while ignoring the other side, the choice-in-a-vacuum, which is not a real-world choice
). More straightforwardly, sure -- the guy maybe sells guns to dictators. Or maybe he sells the guns to freedom fighters
, instead. Or maybe he sells them to a government which is fighting terrorists
. You can argue for a dealer choosing his clients, but that's not
the argument being made, the argument put forth is that "all arms sales are bad
, and anyone who sells them is doing wrong and evil". Some sellers WILL do wrong and evil by selling them to bad people. So the right thing is to leave freedom fighters, and government anti-terrorists unarmed
That's just brain-dead.