How Do You Know if You Own a Gun?

Scientists say there's no scientific evidence to support the idea that every gun leaves unique marks on a bullet. Juries crave certainty, so an expert can't stand and tell you for certain that this is what it is - they'll just give you odds. Judges have finally started putting some limits on what experts are allowed to testify about after decades of sin feedback from the scientific community. And now its going to make it harder for law enforcement and prosecutors to win convictions because their credibility will be questioned.