The cutting-edge performance packed into modern bullet design is no accident. The ballistics, metallurgy and physics poured into those critical components allow them to perform designated duties with enviable reliability. Many are jacks of all trades, but when it comes to stopping an up-close attacker with authority, never bet your life on a master of none. Hollow-point bullets are lifesavers, but also drop big game with authority and reign supreme in long distance.
Today’s bullets are lightyears ahead of their predecessors and constantly improving as the industry embraces new technology. That evolution, however, has not endangered the original hollow-point design for some good reasons.
What Are Hollow Point Bullets?
The traditional definition of a hollow point is a bullet with an empty cavity in its nose—or front. Today there are polymer-tipped versions that deliver identical or enhanced performance that blur the line, however.
Regardless of the cosmetics, every hollow point bullet’s mission is to expand (upset) when that cavity up front fills with a gelatinous material—like tissue—at high speed. Hydraulic pressure gets it done, building quickly during the projectile’s travel in the medium, ultimately forcing the malleable sides to widen.
The performance comes with a concern, however. The bullet’s cavity can collect debris and, if it’s plugged when it reaches the target, it could fail to expand.
The air it encounters during flight isn’t the problem, but any animal hide, drywall and clothing it passes through is. Most big game is hairy, and perpetrators usually add a layer of clothing. If that hollow point collects fiber, T-shirt material or leather, it can compromise terminal performance.
It’s a problem law enforcement wrestled with for decades, but Federal Ammunition came up a remedy years ago with its Hydra•Shok bullets. They have a traditional nose cavity, but a post in the center ensures expansion, even after encountering barriers.
Hornady led a polymer revolution not long ago with its Critical Duty and Critical Defense lines. The bullets are hollow point in design, but a synthetic material that fills the cavity is pliable enough to generate the hydraulic pressure required for complete upset. The former is designed for law enforcement use, capable of passing through wood, glass and some metal without losing its fight-stopping performance. The latter is tailored for civilians who won’t likely ever need to breach doors, or stop cars, but still need the bullet to expand after passing through clothing. It’s a versatile approach now available from a variety of manufacturers.
When performing as designed a hollow point bullet increases diameter significantly. A 9-millimeter, for example, might upset to a width of 18 millimeters. The increased internal wound channel improves the odds it will encounter a critical organ or artery along the way.
That wider, flatter profile also adds friction, slows the bullet and dumps its force faster into a target. That sudden transfer of energy isn’t enough to send an attacker flying—regardless of what they portray in movies—but that “shock” can traumatize directly adjacent tissue or organs. The so-called temporary wound channel increases effectiveness, although scientists still debate precisely how much. There is, however, no doubt it plays part in the well-documented stopping power of hollow points.
That sudden reduction in speed decreases the chances of the bullet passing completely through the target and continuing to parts unknown. The asset is a valuable one if attacked on the streets with innocent bystanders downrange or children are inside an invaded home.
Expansion on impact isn’t always an exclusive mission for hollow points, though. Many rifle bullets designed for precision at distance also have a small cavity in their nose, although the diameter is relatively tiny when compared to those in self-defense versions.
That hole, more technically called meplat, is there to improve aerodynamics, but it’s not simply a matter of adding a cavity. It must balance correctly with bullet diameter and a variety of other factors for it to fly truer and flatter. The designs, including the Sierra MatchKing line—with decades of championships to its credit—work extremely well. Their primary purpose, however, is not one-shot stops.
Newer, polymer filled designs are something of a hybrid approach ideal for hunting. They maintain some of the aerodynamic advantages while providing the reliable expansion needed to fill big-game tags.
Uses of Hollow Points
For home or self-defense missions, there’s no denying the hollow-point bullet’s lifesaving advantages. Law enforcement originally harnessed their ability to stop criminals with authority, but they quickly made their way to the commercial market. Today’s versions are better than ever before. They can pass through barriers without collecting performance-robbing debris, expand at lower velocities and do it reliably.
Many of today’s hunting hollow-point hybrids also harness the advantages, but are designed to penetrate tough hide and hair before upset. The principle is similar, but different, with a smaller cavity up front than those designed for personal protection.
Hollow points also thrive when it comes to connecting with a rifle at long distance. Expansion—if any—is not the primary purpose, however.
Hollow Points Vs. FMJ
A full-metal-jacketed (FMJ) bullet has a coating of metal across the exterior—usually a copper alloy—different than its interior material (traditionally lead). The design increases the odds it will retain most or all its original diameter and aerodynamically sleek profile after striking a soft target.
That’s a huge drawback for hunting or self-defense. It compromises energy transfer without that added friction and wound channel diameter is the same size as the entry hole.
FMJs, however, are less expensive than hollow points. For that reason, they are a great option for high-volume practice or testing on a budget. They are also reliable and accurate—although rifle precision isn’t up to that of today’s sleek target bullets.
Hollow points first appeared in bullets made from pure lead. The metal is malleable enough to flatten when striking a surface at high velocity. The original design still performs well, but lead has a habit of breaking into smaller pieces with a high-velocity impact. When that happens, the force carried by a single, hard-driving projectile distributes among multiple chunks. Cumulative energy remains the same, but divided among smaller parts it often results in all of them failing to drive convincingly deep.
The industry’s solution is the jacketed hollow-point (JHP) design, the most common today. The approach is simple. Cover the exterior surface of the bullet’s lead core—hence the “jacket” term—with a material capable of clinging to and holding the projectile together. Keeping the energy in a single piece maximizes penetration while the mushroom shape it takes increases energy transfer.
Some JHPs have the jacket unbonded and others use physical, chemical or other means of binding that covering to the lead. There’s really no consensus if one is better than the other, although all have proven extremely effective at what they do.
The jacket also lends itself to controlled expansion—bullet upset at optimal depth. Some companies score the surface to get that done, others use a notch and there’s no shortage of variations or new techniques explored each year. JHP’s on the other hand, have a smooth exterior and any upset they experience is either absent, uncontrolled or unpredictable.
There are also monolithic hollow points made of a single material—copper being the most common. Most have a construction that includes sections designed to generated the desired expansion in a predictable manner. Their performance is on a par with JHP bullet designs.
Do You Need Hollow Points?
If home- or self-defense is the mission, there’s no denying hollow point bullets reign supreme. The design is the top choice for professionals, instructors and knowledgeable enthusiasts alike.
There are, however, considerations. Some pistols are finicky and refuse to feed every cartridge wearing a big gaping hole up front. The time to practice your tap-rack-access drills is not during a felonious assault.
The solution is to try different hollow point loads. Run through enough of the cartridges that you’re confident they run, unfailingly. Those annoying stoppages are rare with today’s CNC precision in gun manufacturing, but they do happen. Odds are good any of the polymer-tipped hollow points, thanks to their more-rounded profile, will be unfailingly reliable.
Today’s micro-compact carry pistols wear short barrels. Using cartridges tailored for a full-size gun can result in the bullet exiting below its performance window. Too slow and it may perform like an FMJ. Manufacturers have addressed the problem with elegant bullet improvements and new designs. If your self-defense choice fits in your pocket, consider one of them.
Hollow points also reign supreme when it comes to big-game hunting. An FMJ may penetrate that animal’s tough hide and keep on trucking, but today’s high-performance loads pass that barrier with ease, yet expand at the optimal time. And, as for connecting with a rifle at long distance, the difference those tiny holes/meplats make is often whether you get to stand on a podium finish or collect yet another participation prize.
When there’s a trophy or life on the line, hollow points reign supreme. For punching paper, practice or plinking, FMJs are the economical choice, though.