...when every factory and independent lab test concludes that 90% of those defensive hollowpoints needs a minimum velocity to open up, that cannot be provide by that 3.2 inch barrel?
I find this statement dubious. What caliber, loads, and firearm(s) are we discussing here? Who did the tests and when?
Most recently-published ballistics tests using modern JHP loads in the major combat/LE calibers (9mm, .40S&W, etc.) seem to have the exact opposite success rate- most shots do
open up, even when fired from short barrels through intermediate barriers such as auto glass.
The 90% failure rate echoes tests published in the 1980s, but bullet design has come a long way since then.