[cashflyer]

I know a few cops who have been using 40 for a couple of decades now. I don't think it's really a new persoanl choice, but maybe AA is making it a mandatory switch...

Colloquially, 40 = .40 = 40S&W = 40 cal.

9mm is around .35"
10mm is just over .39"
.40 = .40"
.45 = .45"

I remember 10mm getting a little interest, but I think .40 won out in popularity.

The advantage is more bullet weight and surface area = more "stopping power" and less "penetration".


Now this is assuming you are sure that AA is switching to 40s for handguns, and not just switching to 40s of malt liquor.