One of the most frequently asked questions related to firearms and ammunition is the difference between full metal jacket (FMJ) and “hollow point” projectiles, bullets, and ammunition. When we talk about FMJ or hollow points, the term technically refers specifically to the bullet itself, or the projectile that travels down the barrel of a firearm at high speed and then (hopefully) hits the target. Ammunition, or cartridges, may be loaded with various types of bullets, and these distinguishing terms help people identify what type of bullet the cartridge in question is loaded with. Let’s go over what each of these terms means, and discuss why you might use one over the other in certain situations.
What is a full metal jacket (FMJ)?
Full metal jacket or FMJ refers to a type of bullet with a soft lead core covered by a copper, brass, cupronickel, steel, or other metal outer sleeve or “jacket,” usually leaving the base of the lead bullet exposed. FMJ rounds for high-speed rifles are typically spire-point or “spitzer” in design, but there are round-nose FMJ rifle rounds uncommonly available in some calibers, and for slower rifle cartridges, particularly for lever-actions, flat-point FMJ bullets are more common. FMJ handgun rounds for semi-automatics are most often round-nose in profile, but there are some truncated cone or other shapes of pistol FMJ bullets.
However, the key feature of any FMJ bullet is that the nose and sides of the lead bullet will be completely covered, or jacketed, with a harder metal, most commonly copper in the case of handgun bullets.
Sometimes ammunition is sold with copper-plated lead bullets or with “bonded” coatings that are electro-chemically plated to the lead core, rather than having the lead core swaged or otherwise formed mechanically into the outer metal jacket, and these are occasionally still called FMJ bullets, though technically they should more accurately be termed “bonded” or “plated” bullets. This type is also sometimes called “TMJ” or Total Metal Jacket, since the base is covered with a copper outer surface, along with the sides and nose. They are less common than true FMJs, at least in factory-loaded commercial ammunition.
How FMJ bullets work, and the pros and cons
The two primary benefits of FMJ bullets are that they are less expensive (generally) than quality jacketed hollow point (JHP) bullets (which we’ll discuss in detail below), and FMJ cartridges generally feed more reliably in more firearms than JHP ammunition does.
First, let’s talk about cost. Since FMJ ammunition is by far the most common in the USA, the economy of scale, along with the simpler process of manufacturing FMJ bullets, means that ammunition loaded with FMJ is almost always significantly less expensive than JHP ammunition. This means you can afford to shoot it more, and for informal target-shooting purposes, FMJ ammo works just fine.
Secondly, FMJ ammo is the gold standard when it comes to ammunition that feeds reliably in semi-automatic handguns and rifles. When someone is experiencing jams, misfeeds, or other reliability issues with a firearm, one of the first recommendations offered by knowledgeable people is “Try some quality FMJ ammunition.” In many cases, handguns and rifles will be nearly 100% reliable with FMJ ammo, while they may choke on certain types of JHP. There are gunsmithing procedures and methods that can make a firearm more reliable with JHP ammo, but in nearly every case, a firearm will be more reliable with quality FMJ ammo than with JHP.
One potential “pro” in favor of selecting FMJ ammunition, particularly for a smaller defensive handgun, is that FMJ bullets provide increased penetration along with better reliability. FMJ ammunition often will penetrate a full 18” block of ballistic gelatin, and in some cases, two full blocks. This means that for smaller calibers such as .22LR, .25 ACP, .32 ACP, and even .380 ACP, a short-barreled concealed-carry handgun firing FMJ bullets will have a better chance of reaching the vitals of an attacker compared to JHP bullets fired from the same gun. For this reason, many people who choose to carry these diminutive calibers for defense frequently also choose to load their firearm with FMJ ammunition, both for the increased reliability provided, but also for the increased penetration.
However, this increased penetration of FMJ bullets may also be a potentially serious downside, depending on the situation and the caliber in question. For example, a standard 9mm FMJ bullet fired from a common CCW pistol can often penetrate 27-32 inches of ballistic gel or more. This means it will likely pass completely through an attacker and still have sufficient velocity to injure or kill an innocent bystander. You are legally responsible for every bullet you fire, and overpenetration is a potentially serious liability for FMJ in common “full-size” defensive calibers. (.38 Special, .357 Magnum, .40 S&W, .45 ACP all produce similar or greater penetration results compared to 9mm when firing FMJ ammunition.)
What is a hollow point, hollow tip, or JHP bullet?
A hollow-point bullet–or you might hear the term “hollow tip”–is a bullet with a hollow cavity in its nose, either molded there during the casting of the lead or solid copper projectile or machined or formed by a punch after the bullet is swaged or cast, later in the process. Though there are hollow-point bullets that are completely made of lead, copper, or bronze alloy, the vast majority of hollow-point bullets for modern defensive use in handguns are “jacketed hollow points” or JHP bullets, which have a copper, brass, cupronickel, or other harder metal jacket that fully encloses the base and sides of the lead bullet core, but is, of course, open at the hollow point in the nose. This jacket helps reduce leading in the bore.
High-speed rifle bullets that are open at the tip are usually called open-tip or “open tip match” (OTM) bullets, rather than JHP, but in slower-moving rifle calibers like .45-70, .30-30, or the like, you may find some cartridges labeled JHP (although “soft-points” are more common for hunting rounds in those calibers).
For defensive handgun ammunition, JHPs are by far the most common and recommended choice.
How hollow points work, and the pros and cons
The reason for the hollow cavity at the front of a defensive or hunting hollow-point bullet is it weakens it, and creates an area that can be easily deformed when the bullet impacts a soft material like a bad guy, a game animal, or ballistic gel. A jacketed hollow point’s (usually copper) jacket reduces or prevents lead deposits in the bore of a firearm as mentioned above, and may have the additional benefit of aiding in the controlled expansion of the JHP bullet, and preventing fragmentation and erratic performance.
So why would you want a bullet to deform or expand when it hits a soft target? It’s all about energy transfer and greater damage potential. We talked above about how FMJ bullets fired from common defensive handguns often completely penetrate an assailant or animal, and retain enough velocity to injure or kill one or more bystanders on the other side. This means that the energy of the bullet is not being effectively transferred into the intended target.
A hollow-point bullet, on the other hand, is designed essentially like a parachute, and as the nose of the bullet opens or “mushrooms” in soft tissue and the bullet is deformed into a wider, flatter shape, it dramatically slows down inside the target, dumping all of its energy quickly and ideally stopping inside the target.
This is one of the primary benefits or “pros” in favor of JHP ammunition for defensive use, particularly in handguns. A properly designed JHP bullet creates much more damage and delivers more energy into the target than FMJ bullets do, particularly when we’re talking about handgun rounds. (High-speed FMJ rifle rounds commonly deform, break, tumble, and/or fragment when hitting soft targets, so they remain very effective at wounding or killing despite their non-expanding design.)
We say “properly designed JHP bullet” because a JHP bullet that is too tough, has too small a cavity, and/or is improperly loaded for the specified speed range of the intended caliber, may not expand at all. Laboratory ballistic gel testing of defensive handgun rounds has shown that sometimes certain JHP bullets simply don’t expand properly, either because they are not moving fast enough to expand, or the hollow-point cavity becomes plugged with bits of clothing or both.
Another potential downside to improperly loaded or improperly constructed JHP ammo is that it may expand TOO well and too quickly, dumping all of its energy in the first few inches but stopping before it reaches the vitals of the intended target. This can happen when a handgun-specific bullet is driven faster than its intended impact velocity, perhaps in a magnum caliber or when fired from a carbine or rifle, rather than from a handgun. The FBI has performed studies on the effectiveness of bullets in shootings, and their recommendation is a penetration depth of between 12” and 18” in calibrated ballistic gel. When bullets are pushed faster than they are designed, they may break up or stop in the first 4-10 inches, which is not ideal.
So, it’s important to select JHP handgun ammo that’s been shown in various tests to perform in the way you desire. Most of the modern JHP loads from well-reputed ammo manufacturers like Speer, Hornady, Federal, Winchester, and Remington usually perform acceptably well in ballistic testing.
As we mentioned earlier, FMJ ammo is almost always more reliable and less expensive than JHP ammo, so those are a couple of other potential downsides to JHP. Quality JHP defensive ammo from reputable manufacturers is usually acceptably reliable in modern, quality handguns and carbines, but it’s important to test it for yourself, and this can get expensive. While FMJ “range ammo” might cost around $.20 per shot in a non-“panic” market, the premium JHP defensive loads are often at least $.80 per round, and often can cost a buck or more per pop. If you practice often with your defensive handgun (which you should), this can be cost-prohibitive. So many people practice with FMJ loads, and carry JHP ammo, ideally rotating it/shooting it often enough to ensure quality and reliability in their carry ammo.
The “Hydrostatic shock” argument with handgun rounds
Hydrostatic shock is a controversial topic in the firearms world and has been for over 70 years. In simple terms, hydrostatic shock is the concept that a bullet can produce a pressure wave that causes “remote neural damage,” “subtle damage in neural tissues,” and/or “rapid incapacitating effects” in living targets such as humans and game animals.
Some people say that it’s possible to generate hydrostatic shock with handgun rounds, and generally, these people say that hollow-point bullets are superior to full metal jacketed bullets for this reason.
However, much evidence has been presented to suggest that pressure waves, or sound waves, capable of being induced by the impact of a projectile, are simply not significant enough to produce the effects claimed by proponents of the theory.
Most evidence suggests that hollow-point handgun bullets may (eventually) incapacitate assailants by crushing tissues, tearing blood vessels, and breaking bones, and by delivering all of their energy into the intended target, rather than any “remote neural damage” resulting from hydrostatic shock. Expanding JHP handgun bullets are undeniably better at doing so than FMJ bullets.
Despite some very enthusiastic debate on both sides over the decades, most people will agree that IF hydrostatic shock is possible with small arms such as rifles and handguns, it is more likely to occur at bullet impact speeds greater than 2,200 feet per second and at energies of greater than about 500 ft/lbs. These conditions are easily attainable with common high-speed rifle cartridges like the .223 Remington/5.56x45mm NATO, but in handguns, this level of performance is pretty rare, and basically impossible using common defensive handgun cartridges fired in common defensive handguns.
What are the uses for each type of ammunition?
We’ve gone over the pros and cons of FMJ and JHP ammunition above in a defensive and economic context, but to quickly review, JHP is the clear choice for concealed carry or defensive use (with some exceptions for the truly underpowered ‘pocket gun” calibers mentioned above), due to its greatly reduced potential for unintended overpenetration and its increased ability to deliver incapacitating damage to an assailant, while FMJ is best for range practice, inexpensive plinking, stockpiling, and potentially competition/target shooting use. This brings us to the next point to consider.
Accuracy and target shooting: Which is best, FMJ or JHP?
Depending on your shooting discipline you may be required to use FMJ or non-hollow-point bullets in your handgun match ammo. This can be frustrating for those shooting “Bullseye”-type accuracy competitions where consistency in your ammo is absolutely vital, and the utmost accuracy out to 50 yards is the goal. Quality JHP bullets have traditionally been more consistent at producing top-tier accuracy compared to FMJ bullets, as discovered by organizations like the Army Marksmanship Unit.
[Image courtesty of U.S. Army Marksmanship Unit]
However, quality FMJ bullets from reputable manufacturers can be very accurate. For practical shooting like USPSA, IDPA, or multigun competition, a sufficiently accurate load with the most quality FMJ bullets can likely be achieved, though some people still insist on loading JHP “match” bullets where legal for competition. Hornady’s HAP bullets are a hollow-point design without the flutes that increase regular expansion and are intended solely for consistent accuracy for target shooting, rather than for defensive use.
Defense against large/dangerous animals: FMJ or JHP?
This is an area where the previously discussed “con” of overpenetration of FMJ bullets turns into a “pro.” Bears, feral hogs, and other large, tough animals have a lot of fat, bone, muscle, and thick hides/hair protecting their vitals. Ideally, you would be using a powerful rifle against such beasts, but if you find yourself using a handgun, a solid hard cast bullet, or an FMJ is usually considered preferable to even the best JHP.
Why? Because handgun-oriented JHPs are designed to expand relatively quickly and deliver their energy in the first 18” of tissue, but that’s in an ideal scenario. After hitting bone, tough hide, etc. the JHP bullet may deform or otherwise underperform, or indeed it may expand too quickly before it reaches the vitals of the animal. In these situations, particularly if you’re armed with a 9mm or another non-magnum handgun, a deep penetrating FMJ or hard-cast non-expanding bullet is preferred. However, for hunting deer-sized game, a quality JHP handgun load may be more appropriate.
Store your guns and ammo in a Liberty Safe
Whether you choose FMJ or JHP ammunition or both, it’s important to keep your guns and ammunition securely locked away from children and unauthorized users. A great way is in a USA-made gun safe from Liberty. We have a wide variety of sizes, capacities, styles, and models of safes at multiple price points, so be sure to check out our online catalog or visit a Liberty safe dealer near you.