You have bought your first gun for whatever reason and you are trying to understand what type of ammo to buy and how to understand the different types of ammo out there. For the sake of time, I will keep this post to pistol or handgun ammo. Even then, this will only scratch the surface.
There are primarily 2 types of ammo for handguns out on the market, and that is Full Metal Jacket (FMJ), and Jacketed Hollow Point (JHP). There are other more “specialty” types of pistol ammo, such a snake shot (a pistil round that has lots of BB’s in it), Frangible (more likely to disintegrate when hitting hard or soft services, common for training), and even tracer ammo (emits light so you can follow the path of the round). But I will only talk about the 2 primary types in this article.
To understand the difference between an FMJ and JHP, think of it like this. FMJ for practice and JHP for self-defense. The look of the two is simple, JHP has a hole in the tip of the bullet and FMJ do not, this is based upon the intended purpose of the JHP. When a JHP hits tissue (human or animal), or something like water, it is meant to expand, which spreads the energy over a greater area, and is less likely to exit the body. The FMJ is simple a hole punch, it is meant to make holes and pass through, nothing more or less.
The reason the JHP is designed to do what it does, is that by expanding, it has a better chance to cause more internal damage in the attacker, and more damage means more bleeding, and the faster the attacker takes the room temperature challenge. Yes, an FMJ can and will kill someone but you have a greater chance of the FMJ exiting the body as it does not expand, and expansion makes the bullet slow down. You are responsible for every bullet you fire, and if you use FMJ and they exit the attacker and kills a kid, you are responsible for that death, and in some states can face prison time.
So, what JHP do you choose for your gun? Well, there are many options, and I highly suggest getting something similar to Federal HST, Winchester PDX1 (or Rangers), Speer Gold Dot, or if you can find them Hornady Critical Duty (not Critical Defense). You will also need to know if your gun can handle hotter loads, and a hotter load basically means more powder and higher pressure in the chamber. To know if yours can handle hotter loads, call the manufacturer and ask. I personally wont use anything over +P (plus pressure), anything over +P, is typically harder to manage when shooting.
So, what weight bullet do you buy for the JHP or FMJ? I typically suggest buying the same weight in FMJ and JHP, as this allows you to practice with the same weight bullet as your carry or defense round. However, for some calibers like 9mm that is easier said than done. The most common 9mm FMJ is the 115 grn, followed by 124, then 147. The heavier the most expensive. For 9mm JHP the most common is 147 grn, followed by 124, then 115. Generally, the heavier the bullet the more it will punch through, so for the winter, a heavier bullet is great. I tend to stay in the middle with 124 grn.
Other calibers like 40 Smith and Wesson, and 45 ACP, the most common JHP and FMJ are the same, so you don’t have to search if you want to match bullet weights. The lighter the bullet the faster it goes, and if you want to shoot suppressed (or using a silencer) you need the heavy bullets, as they often don’t break the sound barrier. Heavier also means more energy into the attacker.
For reference, I will stick to the basics when I shoot, I will mostly reload 115 grain 9mm, as they are the easiest to get, but I will buy factory 9MM NATO (124 grn +P) as that matches my carry load. For 40 S&W it is simple, 180grain for both, and 45acp same thing, you can get the 230 grain for both. I do not recommend JHP ammo like G2 research RIP ammo, or the liberty defense ammo. This is a topic for a whole different article.