You may be confident that the data proving a measurable increase in the effectiveness of handguns in stopping threats since the adoption of FBI testing standards exists, but I remain skeptical.
In a discussion linked here some time ago, Jason Vanderbrink, president of Speer, CCI, etc., described the testing they perform and the way the results are reflected in their products. He went on to say that they remain in continual contact with the FBI and with LEO users to stay abreast of field performance.
It stands to reason that they cannot gather scientific measurements from the field, but that what they are looking for is factual data that would indicate performance problems with their products in actual usage.
How would you do it?
These corporate leaders are responsible for the protection off shareholder assets and for ensuring adequate returns on the substantial investments made in product design, materials development, production engineering, and testing.
Notwithstanding the testing standards, today's premium defensive ammunition is far superior to the products of yore, in terms of penetration, holding together during penetration, reliability of expansion, expansion after having gone though fabric, and performance in passing through solid barriers.
Why would anyone doubt that the ammunition performs better in the field?