When looking at centerfire rifle cartridges for hunting, I’ve often been puzzled by several that have acronym designations implying some particular capability. You’ll see this on cartridges/bullets designed for small varmints, those designed for large dangerous game and everything in between. An example is the Hornady GMX (which will be explained later). As if the letters weren’t bad enough, you’ll often find terms on ammo boxes such as Interlock, AccuBond, Partition, Ballistic Tip, Power Point, etc. So what do the letters and terms mean to a person wanting to buy hunting cartridges or bullets for reloading?
A bullet, of course, is the projectile part of a cartridge. A centerfire cartridge has a bullet, case, powder and primer. I am not an expert on this topic. I’ve never been employed by a firearms-related industry (it would have been great, though). I’m just a guy who tried to learn what letters behind bullet identifications mean. That, in turn, led to learning about bullet design and characteristics.
My research has been on .30 caliber bullets. Caliber is a measure of a bullet’s diameter and it must match the caliber of rifle barrel you are shooting the bullet through (basic stuff, right). I focused there because I own two .30 caliber rifles, one an AR style and the other a traditional bolt-action hunting rifle. The same research can be done on any caliber by anyone who has elementary computer skills. Your favorite search engine makes it easy. Simply type in the designation of the bullet (including brand name and other identifications), then it is usually best to click on the manufacturer’s website among the many choices for the information you need. An option is simply going to manufacturer’s websites, which will let you search for specific products. On most websites you’ll find detailed information about how the company’s bullets are constructed and related details.
Full Metal Jacket
The same type of research can be done on FMJ bullets (there’s those letters again) as well as hunting bullets. FMJ is an acronym for “full metal jacket”, which is a lead-core, copper-jacketed bullet that is not intended to expand after impact. They are used primarily for target shooting or combat. Hunting bullets are designed to expand after impact, but in a controlled manner. Effective expansion has been a major emphasis of research by manufacturers.
It is helpful to be familiar with bullet design. The tip can be flat, open-tipped, rounded or pointed. A pointed-tip design is called a spitzer, and many modern hunting bullets have a polymer spitzer tip. By the way, just because a bullet has a slightly open tip with a small hole doesn’t mean it’s a “hollow point”—it’s probably just a remnant of the manufacturing process. The part of a bullet that has slanted sides behind the tip leading to the thickest part of the bullet is the ogive. If a bullet has one or more groves in the thickest part, they are called cannelure. Bullet bases are flat, or boattail (BT) if they have a slight taper near the base. All of these parts of bullet structure have been modified by manufacturers in various ways to develop products for specific purposes.
The most significant factor in a bullet’s field performance is its caliber and weight proportioned to the size and type of game being hunted. Smaller calibers and lighter bullets are okay for small, thin-skinned animals. Larger, tough-skinned animals require larger calibers and heavier bullets. You should be able to find a good choice for any hunt. One well-known manufacturer, for example, makes .30 caliber bullets with weights of 110, 125, 140, 150, 155, 165, 168, 170, 175, 180, 190, 200, 210, 220 and 308 grains. One ounce equals 437.5 grains. Not all of these bullets are designed for hunting, but you get the idea of how many options are available.
The Best Choices
Within every caliber of rifle, you can find a range of bullet weights for it (but often not as many as in this example of the popular .30 caliber). That being stated, exactly which choice is best for specific game in every caliber has been debated around campfires, in gun stores, in magazines and on websites ever since the development of modern arms. There’s never just one acceptable choice, but you have to pick one within a practical range that’s appropriate for the environment and terrain that you’ll be hunting in. A good example is not paying for higher cost cartridges (or bullets) that are designed for long ranges if you are hunting in hilly, brushy terrain. And, in the December, 2017 issue of Gun Digest, in conclusion of an article titled “Energy and Killing Power” author Phil Massaro stated, “Be sensible about it, and don’t try to kill an elephant with a sewing needle, nor swat a fly with a sledgehammer.”
Starting with the development of modern ammo, hunting bullets have been manufactured with a soft lead core and a harder coating of copper on the outside. An innovation that became popular in the 1980s was a chemical bonding process between the two metals for a more controlled expansion and less fragmentation after impact on an animal. Thus, you’ll see marketing terms such as InterBond, Core-Lokt, and AccuBond. There are partitioned bullets on the market, which have two separated lead cores. Polymer tips came on the market a few years ago and they provide an increase in aerodynamic qualities.
Beware of Marketing Hype
Although bullet makers have lots of test results to back up sometimes lofty claims out of marketing departments, there’s no better way for a hunter to verify the effectiveness of these designs than field experience. Articles in gun and hunting magazines and/or websites can be helpful sources of information since their writers often have the ability to use several types of bullets on a variety of game. All bullets on the market today will perform reasonably well according to their manufacturer’s claims, and it often comes down to your preference of manufacturer.
All-copper or copper-alloy bullets are more recent innovations. They are also called monolithic bullets since they are made of one metal and not a combination of lead and copper. They are lighter than their jacketed-lead counterparts of equal size and will achieve higher velocities if the cartridge is otherwise the same. They also retain nearly 100 percent of their weight after impact, while lead-core bullets will lose about a third of their weight (plus or minus) after impact. For most hunters it’s a matter of personal choice to use monolithic or jacketed-lead bullets, but there is a growing public/regulatory interest in the use of lead-free bullets and it may be required where you live.
An important numerical value related to bullet design is the ballistic coefficient (BC). Technically speaking, it is a measure of air drag. Relevant factors include a bullet’s weight, diameter and aerodynamic characteristics. A higher BC means it will retain more velocity in flight, and thus retain its optimum expansion capabilities when it reaches the target. Bullet manufacturers provide this value, either on their website or with a direct inquiry.
There’s a misconception that BC is a measure of accuracy. It is not. First, let’s address the word accuracy. It means the ability to hit a point of aim. There are multiple factors involved: How well all the components of a cartridge are made, how well your rifle is made, the quality of your scope if you use one and, most of all, your skill as a shooter. To be a skilled shooter you need to know how to establish a stable shooting position, have mastered trigger pull technique, know how to adjust point of aim to allow for bullet drop over distance, and how to compensate for wind and other environmental conditions.
It’s more correct to say BC has a close correlation with precision. Precision is a bullet’s ability to provide consistent performance. A BC number indicates a bullet’s ability to minimize in-flight variables such as wind, typography, atmospheric pressure, etc. The higher the number, the better a bullet can do this. That enables consistency of performance. BCs for .30 caliber hunting bullets range from about .200 on the low end up to those approaching .600. Most fall within the .250 to .500 range.
Bullets with spitzer points and boattail bases will inherently have higher BCs than bullets with other designs. Spitzer-pointed bullets cut through the air better than those with more of a rounded point. Polymer points have increased bullet precision because they can be manufactured with less variability than can be induced into the points of metal bullets. Boattails aid precision by having better aerodynamic qualities than flat-base bullets, and they help a bullet line up better with the case mouth during cartridge construction. Bullet weights on the heavier side of the spectrum of each caliber also tend to give higher BCs with all other cartridge components being equal.
The choice of bullet, however, is only part of the equation in determining performance in the field. The cartridge case has to contain enough powder to push a given bullet weight with enough velocity and downrange energy to insure clean kills. The cartridge case design and capacity are key. A .30-06 cartridge, for example, pushes a .30 caliber bullet a little bit faster than a .308 cartridge. Using a .300 Winchester Magnum cartridge, as another example, gives that bullet a big boost in velocity over either the .30-06 and .308.
Another factor influencing a bullet’s velocity is the length of barrel on your rifle. Shorter-barrel AR rifles may be great for some uses, but not the best choice for hunting unless you restrict yourself to shorter-range shots. The type of powder in the cartridge also plays a role, and there are about 150 choices. You don’t have to worry about that if you buy manufactured cartridges since you can assume the companies that offer them have selected one that provides optimum performance. The same is true if you consult loading manuals when hand loading cartridges. Be careful if you are a hand loader and wish to experiment with powders because you can induce too much pressure in the rifle chamber with unpleasant results on your rifle and/or your body parts.
There’s one more thing about what you can expect from a bullet regarding precision—that ability to have repeatable performance. Every component of a cartridge, every component of a rifle, and every component of a scope are manufactured and assembled within acceptable tolerances. There’s a bit of plus or minus in all of them. Typically, the more you pay for bullets, a rifle and a scope, the tighter the tolerances you get. For hunting purposes, a good point of reference is that a moderately skilled shooter, using a bench rest, should be able to see all of the bullets sent downrange impact within 1 inch of your point of aim at 100 yards. It’s not uncommon to have a particular rifle shoot a certain weight bullet a bit better than others, and it’s probably a matter of how all the tolerances of all the components interplay with each other.
The goal of every hunter is a quick, humane kill. Even if you have excellent choices of firearm, optics, cartridge and bullet, never exceed your tried and true capabilities as a marksman. For most of us, a good rule of thumb is to not attempt shots longer than 400 yards. Be sure you know how to adjust your point of aim to compensate for significant differences in elevation between you and the target. Shot placement is critical, and be sure to know the best points of aim when the animal is broadside, facing you, quartering away, etc.
FMJ = Wounding
Since full metal jacket bullets are cheaper than hunting bullets (unless you buy match quality FMJs), you can find one that’s close to the weight of hunting bullet you prefer and do a lot more practice shooting on the same budget. When you are ready to hunt, it takes only a few of the hunting bullets to fine tune your scope or sights, making necessary adjustments to compensate for any difference in bullet weight. If you think about using FMJ bullets for hunting, don’t yield to the temptation since they are much more likely to only wound an animal. Of course it may be necessary if hunting bullets aren’t available, such as in a TEOTWAWKI  situation. Shooting FMJ bullets at game might be one more entry on a long list of things you’d rather not do but must as a means of survival.
If you put a bullet in the right spot on an animal you want it to be effective. It’s frustrating to spend hours tracking a wounded animal with success of finding it being uncertain. Worse yet is not finding it. You need to assure yourself as much as possible that you’ve selected a bullet that’s appropriate for the hunt.
So, about those mysterious letters. A list of all of the acronyms on the market would be too long, but a few examples are enough to give you a sense of how manufacturers choose them. Berger’s VLD means Very Low Drag; Hornady’s GMX means Gilding Metal Expanding; Nosler’s AccuBond LR means Long Range; Nosler’s CT means Combined Technology; Remington’s PSPCL means Pointed Soft-point Spitzer Core-Lokt; Sierra’s Game King SBT means Spitzer Boat Tail; and Winchester’s Deer Season XP means Extreme Point. Descriptive—yes . Obvious meanings to the average hunter—not so much.
Keep in mind that some cartridge manufacturer brands will have one or more products containing bullets from another manufacturer. Federal cartridges, for example, will have bullets made by their own company, but also ones made by Nosler and Sierra. Remington’s HTP (High Terminal Performance) cartridges are loaded with Barnes’ TSX (Triple Shock, and the X represents the four-petal shape of bullet tips after expansion during testing) bullet! Remington, by the way, has owned Barnes for several years, but other cartridge makers, like Federal, use bullets from companies that have no ownership connection.
If you are a hunter, there are many reasons to enjoy the sport. Killing a game animal is a reward for your planning and effort, and puts meat on the table. The bullet you send downrange has to be effective after impact. Your own research is the best way to know you have selected a good tool for the job when it’s time to pull the trigger.