There is a wide range of ammunition available for most calibers you’re looking to shoot. If you’ve walked past the shelves of ammo, you may have noticed that some calibers have multiple types of bullets that are available. The two most known types are Full Metal Jacket (FMJ) and Jacketed Hollow-point (JHP). Also known as hollow-point for short.
The general rule of thumb you’ll hear from the firearms community is that FMJ rounds are for practice and JHP is for self-defense. This isn’t to say that the rounds can’t cross these boundaries and be used interchangeably but they excel at certain things and you want to make sure you always have the best tool for the job.
We’ll go over some of the key differences in these two types of rounds so that you can make a more educated decision during your next ammo shopping trip.
Full Metal Jacket (FMJ)
FMJ rounds, like their name suggests, are bullets that are soft lead encased in a harder metal shell. This allows the bullet to retain most of its energy while traveling through the air and it deforms less when striking a target or passing through softer materials. These rounds are mostly used for training purposes because they are normally much cheaper to produce than any of the more specialized rounds such as hollow-points. The upside of using FMJ rounds is that they feed fairly easily in most firearms and will get downrange where you need them to be in order to practice your shooting drills or marksmanship without breaking the bank.
The reason that FMJ rounds are not suggested for self-defense is because of the energy and rigidity that they maintain throughout flight and after striking soft targets. An FMJ round is more likely to pass through a soft target and out the other side, into possibly other targets you didn’t intend to hit. This is due to the fact that the bullet does not deform when passing through soft tissues and because of that, it doesn’t lose as much of its momentum. This can have the unintended consequence of not delivering enough force to affect the target quick enough or not creating the type of damage you’d want for self-defense. This isn’t to say that FMJ rounds are harmless and can be disregarded. They are still wads of metal being sent downrange at incredible speeds. But when comparing FMJ to JHP, the FMJ bullet does far less immediate damage to the target as it passes through.
Jacketed Hollow-Point (JHP)
Hollow-points are almost immediately noticed for having a hollowed-out tip in the bullet itself. Some hollow-points now have a polymer or plastic tip covering the hollowed area to give the bullets more aerodynamics like an FMJ round would have, while still having the hollow that allows for expansion of the round. Which brings us to the reason why JHP rounds are most often used and recommended for self-defense.
The main defining characteristic of the hollow-point bullet is to expand, or mushroom, when it makes contact with a soft target. The cavity in the bullet allows the casing and interior of the bullet to peel back and deliver more force into the target. When a JHP round hits a soft target it slows down by a tremendous amount and all of that energy has to go somewhere. The act of slowing down imparts that energy into the target causing more pronounced cavitation and a greater degree of damage. On top of this, due to the round imparting a lot of its forward momentum into the target, the round is less likely to pass through the target carrying much of its energy onward. That is not to say that the round won’t over-penetrate and continue onward, but it is much less likely to do so and even if it does manage to continue moving, it will have much less velocity than it did before making contact.
An important fact to remember is that even though FMJ rounds are most often used for practice at the range, you still want to practice with your JHP rounds as well. Because of the cavitation in the bullet, it sometimes will be picky about how easily it feeds into the chamber of any particular firearm. Thus it’s always recommended that anytime you buy a new brand or style of JHP ammo, you run it through your chosen firearm to insure that they cycle correctly and efficiently. The last thing you want to happen is for there to be a need to use these rounds and then they malfunction in your firearm.
With this information, you should be able to enter the store and know that you’re getting the type of ammo for the job you need doing. Whether that be practicing at the range or arming yourself for defense.