The rounds needed for the handgun you use, depend on the caliber of the firearm. The manufacturer should recommend it. The most common calibers are .22, the .25ACP and the .32. All weapons can used with deadly intent, however, they are not regarded as sufficiently powerful for the purpose of self defense. Any firearm is better than none, and the little .22 has been used successfully many times. A firearm is better than none, and the little 22 has been used successfully many times.Go2FirearmSafety™ lists important ammunition calibers as: The .380 Automatic: The Belgium FN company introduced this around 1912. John Browning was the designer. The reason for this round’s spectacular success is that the .380 is the biggest practical cartridge easily adaptable to smaller automatic pocket pistols. This ammunition was regarded as adequate for a variety of self-defense situations. It is the smallest possible caliber suitable for defensive ammunition. The .38 Special: This is made particularly for revolvers and is one of the most popular cartridges in gun history. It is sold worldwide and comes in two variants- standard and +P. Please note that older .38s may not have the capability to handle the much more powerful +P. It is an excellent idea to verify the ability of the firearms to shoot the +P ammunition. The .38 Special is also known as .38 Colt Special. The cartridge was made by Smith &Wesson, first introduced around 1902. This ammunition was regarded as one of best handgun cartridges and the most balanced. It is also extremely accurate. The 9mm Parabellum is the cheapest of all self-defense rounds. This ammunition is much more powerful compared to .380 ACP, and similar to .380 ACP, it lends itself to the firearm designs that are light and small enough to carry easily. The 9mm is a favored ammunition for concealed carry. When it comes to performance, the 9mm has more power compared to .38 Special- but less than .357 Magnum. It was first fired in 1902, with a Luger made semi-automatic pistol. Ammunition suppliers can easily be found on Go2FirearmSafety™ using our convenient search tool.