I have always considered 9mm Parabellum (also known as 9mm Luger) marginal at best at stopping two-legged predators. For those of you that own a 9mm Beretta Model 92 or Beretta Centurion, be advised that Beretta USA now produces a .40 S&W conversion kit for your pistol. These are complete “top halves” and come with one 11 round .40 S&W magazine. The folks at CDNN currently have these factory-made conversion kits on sale for $149.99. Since these kits don’t include a frame, no FFL is required. If you are one of those folks that has a Beretta 9mm that you don’t shoot much, or if you have both a Beretta 9mm and any other pistols in your battery that are chambered in .40 S&W, I recommend getting one of these kits. The .40 S&W is a fairly reliable stopper. (Not quite up to the benchmark of .45 ACP, but sufficient.) Make sure that you specify M92 or Centurion length when you order.
One key proviso: You should line up a supply of Beretta factory made Model 96G (.40 S&W) 10 or 11 round magazines before you order a conversion kit. Parenthetically, I would consider 5 spare magazines a bare minimum–but 10 or 12 spares should probably meet your comfort level. After you’ve made the switch, I recommend greasing up your old 9mm top half and all of your 9mm magazines with R.I.G. Then seal them up in double plastic bags with a little silica gel desiccant inside the inner bag for good measure. Tuck them away in an ammo can–right next to those cans full of 9mm ammo that you can now resign to the category of ballistic wampum. OBTW, I recommend that you consider having a set of Meprolight or Trijicon tritium sights installed on your new .40 top half. Lay in a supply of at least 1,200 rounds of .40 S&W if your Beretta will be your secondary handgun, or at least 2,500 rounds (or more) if it will be your primary handgun.