Didn’t the FBI run the carousel of caliber testing from carrying a S&W 10mm, then moved to a 357 Sig, and now the 40 cal? I don’t know for sure...Seems they ran ballistic tests on almost every known material under the sky
FBI switched to 9mm about two years ago. They never used the 357sig, though Secret Service, and Air Marshals did (and to my knowledge still do). The latest round of FBI testing included various barriers, but also heavily favored lack-of-recoil and shootability in their selection - their thought, an a logical one it is, is that if you can't hit the target it doesn't matter what caliber you are shooting. - pick a caliber that allows for more hits. FBI testing with glass places the angled glass 18" from the ballistic gel (i.e. the intended target), not 18" form the muzzle and 25 yards from the target. Two very distinct ballistic challenges. The officer did what he felt he had to and it worked, and kudos to that.
