Keeping in mind that handguns generally offer poor incapacitation potential, bullets with effective terminal performance are available in all of the most commonly used duty pistol calibers—pick the one that you shoot most accurately, that is most reliable in the type of pistol you choose, and best suits you likely engagement scenarios.
The following loads all demonstrate outstanding terminal performance and can be considered acceptable for duty/self-defense use:
9 mm:
Barnes XPB 105 & 115 gr JHP (copper bullet)
Federal Tactical 124 gr JHP (LE9T1)
Speer Gold Dot 124 gr +P JHP
Winchester Ranger-T 124 gr +P JHP (RA9124TP)
Winchester Partition Gold 124 gr JHP (RA91P)
Winchester Ranger-T 127 gr +P+ JHP (RA9TA)
Federal Tactical 135 gr +P JHP (LE9T5)
Federal HST 147 gr JHP (P9HST2)
Remington Golden Saber 147 gr JHP (GS9MMC)
Speer Gold Dot 147 gr JHP
Winchester Ranger-T 147 gr JHP (RA9T)
Winchester 147 gr bonded JHP (RA9B/Q4364)
.40 S&W:
Barnes XPB 140 & 155 gr JHP (copper bullet)
Speer Gold Dot 155 gr JHP
Federal Tactical 165 gr JHP (LE40T3)
Winchester Ranger-T 165 gr JHP (RA40TA)
Winchester Partition Gold 165 gr JHP (RA401P)
Federal HST 180 gr JHP (P40HST1)
Federal Tactical 180 gr JHP (LE40T1)
Remington Golden Saber 180 gr JHP (GS40SWB)
Speer Gold Dot 180 gr JHP
Winchester Ranger-T 180 gr JHP (RA40T)
Winchester 180 gr bonded JHP (Q4355)
.45 ACP:
Barnes XPB 185 gr JHP (copper bullet)
Federal HST 230 gr +P JHP (P45HST1)
Federal Tactical 230 gr JHP (LE45T1)
Speer Gold Dot 230 gr JHP
Winchester Ranger-T 230 gr JHP (RA45T)
Winchester Ranger-T 230 gr +P JHP (RA45TP)
Notes:
-- Obviously, clone loads using the same bullet at the same velocity work equally well (ie. Black Hills ammo using Gold Dot bullets, Corbon loads using Barnes XPB bullets, etc…)
-- Bullet designs like the Silver Tip, Hydra-Shok, and Black Talon were state of the art 10 or 15 years ago. Modern ammunition which has been designed for robust expansion against clothing and intermediate barriers is significantly superior to the older designs. The bullets in the Federal Classic and Hydrashok line are outperformed by other ATK products such as the Federal Tactical and HST, as well as the Speer Gold Dot; likewise Winchester Ranger Talons are far superior to the old Black Talons or civilian SXT's.
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Basically all the standard service calibers work when fed good quality ammunition. The platform picked tends to dictate the caliber. For example, Glocks and Sigs tend to run best in 9 mm; the S&W M&P is the first .40 S&W pistol that seems to offer an ideal ergonomic and shooter friendly package; while a properly customized 5" steel-frame single-stack 1911 in .45 ACP is a superb, unparalleled choice for the dedicated user willing to spend a significant amount of money to get it properly initially set-up and considerable time to maintain it. For folks who want a .45 ACP pistol, but don't want to invest the funds and effort into getting a good 1911, they would be better served with a S&W .45 ACP M&P, HK45, S&W 4566, or possibly the SA .45 ACP XD.
Whatever you choose, make sure you fire at least 500 and preferably 1000 failure free shots through your pistol prior to using it for duty. If your pistol cannot fire at least 1000 consecutive shots without a malfunction, something is wrong and it is not suitable for duty/self-defense use.
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The keys are:
-- Cultivate a warrior mindset
-- Invest in competent, thorough initial training and then maintain skills with regular ongoing practice
-- Acquire a reliable and durable weapon system
-- Purchase a consistent, robust performing duty/self-defense load in sufficient quantities (at least 1000 rounds) then STOP worrying about the nuances of handgun ammunition terminal performance.