Ammunition is mass produced, why wouldn't tests on the same make and model suffice? In fact, tests done with new bullets would have favoured JB, because any coating is more likely to be intact.
I disagree...
You really need to be doing tests on the actual bullets fired, or at least upon bullets from the same batch and cardboard ammunition box? The police and the varios prosecution experts had access to all of thdse exhibits yet they chose not to carry out such work. Instead, they chose to use substitute ammunition?