Actually, the real world experience I described occurred 44 years ago. While there have certainly been changes in bullet designs since that time I would suggest that many of those changes are better described as marketing tools than advancements. Lead hasn't changed much, other than becoming more difficult and expensive to locate. Jacket materials have run the gamut from copper-nickel alloys to zinc alloys to aluminum alloys over the years, and differences in performance exist but are not always predictable or even explainable.

Gelatin testing is a comparative method, not a definitive testing tool. All that can be accomplished is comparisons of performance between various projectiles on a particular day, under particular conditions of atmospheric densities, temperatures, and humidity, using specific equipment (handguns, gelatin mixtures, testing tools, etc).

The FBI has been involved in these issues as a central source for collection of data and analysis of performance. As such the FBI is probably the best resource for providing comparative analysis, but even the FBI testing results and protocols are always accompanied by lengthy disclaimers and disclosures.

As far as predicting the terminal effectiveness of any handgun, caliber, projectile, or the other varying factors, under any or all potential field conditions, there is no fool-proof method or empirical facts that apply universally. There are only broad and general guidelines based on known and recorded facts and circumstances.

The one thing that has never changed is that shot placement is the single most critical factor. Everything else involved in handgun selection, caliber selection, and ammunition selection amounts to nothing more than a series of compromises. No guarantees, no warranty express or implied.