[svandamme]

other then impracticality to implement or effectiveness in terms of having criminals not tamper, or not using older weaponry, what's the problem ?

whoever shoots , is responsible for the trajectory and place where his bullet end up
whether or not it is "stamped" or not, the responsibility is already there

anybody who would be hindered by the stamping of his bullets, i would think is somebody who doesn't take this responsibility serious enough?

this stamping would not cause any problems if the guns are used as they should
nobody is going to check serials of bullets at the gun range
if you shoot in self defense, then the self defense would already have been there without the stamps

if anybody steals or misuses a weapon for which you are responsible
then you should have reported it stolen , or taken better care to prevent the mis-use

and let's say somebody recycles a bullet already stamped, let's be optimistic and say you fired rounds in a water tank, and somebody took those bullets , placed them on new shells, and fires them from an old weapon without stamps... i fail to see how that would not leave forensic traces of the second time use, groove marks of the new barrel...