I recently picked up a very informative book, titled [ame=http://www.amazon.com/Modern-Combat-Ammunition-Duncan-Long/dp/0873646282]"Modern Combat Ammunition"[/ame] by Duncan Long, published by Paladin Press. In it the author covers a large majority of commercially available & surplus ammunition for pistols, rifles, and shotguns. Several chapters are devoted to handloading & creating combat cartridges for pistols, rifles, and shotguns; and also covers exotic military and civilian rounds (exploding, AP, APIT, flechettes, riot, etc). In the beginning of the book, he explains the RII ("Relative Incapacitation Index") of a given cartridge, which is based on the amount of disruption caused to ballistic gellatin. Also noted are several studies done by the FBI and other law-enforcement agencies. The book then covers PIR ("Power Index Rating"), which the author considers as giving ratings close to real-world performance, without having to use ballistic gellatin. This equation can be found online as well, and the example given here is from the book. PIR can be figured as such: PIR = (V"squared" x E x B / 12111) x D V= Velocity in Feet per Second E= Energy Transfer B= Bullet Weight in Grains D= Diameter of Bullet To find E; a bullet that expands has an "E" rating of 0.0100. A nonexpanding bullet with a flat-nose that equals 60% of the bullet's diameter has a rating of 0.0085. All other nonexpanding bullets have a rating of 0.0075. To find D; this rating is based on the bullet's diameter given in inches. .2 - .249 = 0.80 .25 - .299 = 0.85 .3 - .349 = 0.90 .35 - .399 = 1.0 .4 - .449 = 1.10 .45 - .499 = 1.15 Here's the example given in the book, using a .38 Special Federal Nyclad expanding hollowpoint: Fired from a 6" barrel, it has a velocity of 915fps (V). It's weight is 125 grains (B) It will expand reliably; it's (E) rating is 0.010 The .38 Special (and .357 Magnum) uses bullets with a .357 inch diameter, so (D) is 1.0 Plug in the numbers- PIR = (915x915 x 0.010 x 125 / 12,111) x 1.0 PIR = 86.41 (round off to the nearest whole) = 86 Here's the PIR Table PIR 24 or less : Target shooting / plinking PIR 25 - 54 : Small Animals / minimal self-defense PIR 55 - 94 : Marginal Self-Defense PIR 95 - 150 : Military or Self-Defense PIR 151 - 200 : Self-Defense Only with enough practice to allow quick recovery from recoil. PIR 201 or more : Hunting large animals only. Recoil and muzzle-blast make these rounds unsuitable for self-defense use. "Modern Combat Ammunition" also gives a percentage of fights stopped with a single shot for several cartridges. These numbers are sourced by the author from firearms expert Evan Marshall, who kept records of success rates for given cartridges in stopping an opponent with a single shot. For example: The 9mm Parabellum with a Federal HP stopped fights with a single shot 72% of the time. The .38 Special with a 158gr. LHP provided a one-shot stop rate of 64%. The .357 Magnum with a 125gr. JHP provided a one-shot stop rate of 91%. And the .45ACP rate 74% one-shot fight stoppers with 200gr. CCI JHPs. For each cartridge, the author considers the effects of standard HP rounds fired through layers of denim / heavy clothing; the effects of rounds with cannelures; cartridge capabilities with +P or +P+ loads, frangible/exotic cartridges (Magsafe, Glaser), and many other variables. Pistol cartridges detailed in this book are: .22 Short, .22LR, .22 Short Magnum, .22 Win Magnum, .25Auto 7.62x25mm, 7.65 Luger, 9x18mm Makarov, 9x18mm Ultra/Police, 9mm Luger/Parabellum, 9mm Luger Rimmed, 9mm IMI, 9mm Major, 9mm Win Mag, 10mm Auto, 10mm Auto Mag, .30 Carbine, .32Auto, .32S&W, .32S&W Long, .32H&R Mag, .380 Auto, .354 S&W, .38S&W, .38 Special, .38 Super Auto, .357 Mag, .357 Maximum, .40S&W, .41AE, .41 Avenger, .41 Mag, .44 Special, .44 Mag, .45 Colt, .45ACP, .45 Hirtenberger Pistol, .455 Webley, .45 Win Mag, .451 Detonics Mag, and .50AE

Just did the math for my Winchester Ranger T-series SXT .40S&W 165 gr. (P/N: RA40TA): (((1140 fps)^2 * .01 * 165 gr.) / 12111) * 1.1 = 194.76 = 195 So, I'm on the upper level of the Self-Defense only with practice. I also shoot it out of the 3.5" barrel of a GLOCK 27. I just shot the IDPA match yesterday and they did a "Power Factor" on my ammo (Winchester White Box .40S&W) on the chrono where they multiply the grain weight by the velocity (my class was a minimum 125,000) and I came out to a ~161,500.