10% Ballistic Gelatin is like the NHS crash rating, only less so. If Car A has a 5-star rating it is probably safer than Car B with a 3-star rating, but by how much? Who knows. What are your chances of being injured? Who knows. It gives you an idea of which bullet expand more for a given velocity, but it does not predict terminal effects. If Bullet A expands more than Bullet B in gelatin, it probably will expand better in tissue. But how that equates to "stopping power"? who knows.