One of our readers recently asked for an explanation of what the abbreviations on the end of ammunition boxes mean. It’s a great question, as it’s not uncommon to encounter store clerks who don’t know, and possibly dangerous to inadvertently purchase the wrong kind.
Knowing what those acronyms mean helps a shooter be a confident shopper who spends their hard-earned money on exactly the ammo they need.
Since most new shooters are likely purchasing ammunition for a new self-defense handgun or a rifle intended for home defense or deer hunting, this article includes terms used for those guns, but excludes shotguns.
Here’s a Rosetta Stone, of sorts, for ammo terms and abbreviations:
Jacket and bullet types
HP or JHP = Hollow Point or Jacketed Hollow Point. These rounds are generally a bit more expensive, and designed for defensive and hunting use. A hollow point is made to open up and “mushroom” or fracture after a short distance of penetration, and is usually made to expend all its ballistic energy within around 12 inches of impact.
The “jacketed” term indicates the bullet itself, which may be lead or a combination of metals, is coated with a layer of metal, usually copper. This improves feeding in semi-autos and controls expansion of the hollow point.
Many gun carriers consider HP/JHP ammunition the responsible choice for self-defense, as it’s less likely to pass through an initial target and into a next. This is NEVER a guarantee in a real-life, dynamic situation. An example is an attack in which the best target area is something like a knee joint, if that’s all that’s visible or all that can responsibly be targeted.
FMJ or TMJ = Full Metal Jacket or Total Metal Jacket. Most common and generally less expensive than HP, FMJ/TMJ ammunition has a usually copper coating over the entire bullet. This is the round of choice for most people for practice and plinking. In general, jacketing helps feeding consistency (dependability) in semi-auto pistols and rifles.
SP, JSP, and Wadcutter = “Soft Point, Jacketed Soft Point,” and Wadcutter refer to bullets with exposed or only partially jacketed lead. These are most commonly seen in ammo intended for revolvers, such as 38 Special, 357 Magnum, and 45 Long Colt. Wadcutter ammunition is less common today, but is still considered a good choice for shorter-range match shooting as it’s highly accurate.
These are common ammunition types. There are variations on these themes, such as jacketed hollow points that have a small polymer plug inside the bullet (which is visible). There are HP rounds which are designed more for fragmentation than simple expansion.
Grain weight, which isn’t relevant to any modern measure except bullets, is also provided on the box end. Heavier bullets may, at first glance, seem a better choice for self-defense or hunting, as they generally achieve better penetration. However, heavier bullets also travel more slowly, which decreases overall impact. It comes down to a matter of personal preference.
Grain weight is far less important than reliability. Not every firearm cycles every round dependably. Grain weight, and while we’re discussing choices, cost, are not always reliable indicators of performance. It’s the interface of your firearm’s construction with that of the cartridge that counts. Practice with your defense or hunting round of choice before you need it.
Rifle and pistol ammunition is generally found with one of three casing types—brass, aluminum, or steel. The case is, physically, the biggest component of your ammunition and holds the primer, powder, and bullet in place. Case material can make a difference in the performance and/or longevity of your gun.
Generally, brass-cased ammunition is preferred, and most accurate. It’s also most widely recognized as acceptable by gun manufacturers.
Aluminum cases may or may not be okay by owner’s manual standards. In some market phases, aluminum-cased ammunition, usually found in FMJ, is more affordable. As of this writing and in my local area, aluminum-cased pistol ammunition is more expensive than some brands of brass-cased FMJ.
Steel-cased ammunition is not recommended for most firearms as it, unlike brass and aluminum, is the same or nearly the same hardness as the inside of your chamber, extractor, and feed ramp, if there is one. Thus steel cases can cause premature wear that, over time, negates the lower price of this ammo. It is common and acceptable to run steel cased ammunition in many foreign-made rifles that were designed around steel cartridges, though pinpoint accuracy isn’t to be expected. The AK and SKS platforms are the primary examples of steel case-friendly rifles.
Boat tail bullets
“BT” is commonly seen on the box end of rifle ammunition. This is the one trait described here the consumer can’t see with the naked eye. “Boat tail” refers to the taper on the tail end of the lead bullet, which is typically jacketed and always sunk into the top of the case. Think of these bullets as being shaped more like canoes than being flat-bottomed, as other bullets are. The taper enhances flight stability and penetration. It’s nothing to fret about; if anything it’ll improve your experience.
Different companies may have different terms—and thus box-end abbreviations–for very similar products. For example, some companies use the letter “n,” as in nose, to signify the shape of the business end of the bullet. Such variables can trip up even experienced gun shop workers. If you’re unsure, ask to see the box, and read it, or search the company’s website. Most ammunition makers do an excellent job with online product descriptions.
That little book can prevent headaches
Your gun’s owner’s manual, which you can search online if you don’t possess, is the best starting point for choosing ammunition. Some manufacturers recommend only American-made, brass-cased ammunition that is guaranteed to meet certain manufacturing standards. Some brands even deny warranty claims if ammunition other than what the manual recommends is used.
The KISS principle
This article covers the most basic components of ammo lingo. Like any new language, there are dozens of variables and application-specific terms that are best learned by doing.
Buyers should avoid getting caught up in spending a fortune on ammunition that’s touted as extra-special in any way—for accuracy, expansion, or the tactical trick of the season. Your best bet is to purchase something that’s reasonably priced and in accordance with the recommendations found in your gun’s owner’s manual. Some foreign-made ammunition is notorious for causing malfunctions in some firearms. So long as your life or a long-awaited game trophy isn’t at stake, and assuming the malfunctions aren’t causing a safety issue, consider that ammunition your go-to for practicing malfunction clearances—an important aspect of shooter competence.
The biggest investment shouldn’t be in ammo, but in time spent practicing the fundamentals of marksmanship. Happy and safe shooting.
Sound Off Gun Carriers! Do you still have any questions? If you do, let us know so we can answer them. Make sure you share this with your friends new to guns so that they aren’t confused the first time they go to buy ammo.
All photos by Team HB.
Thanks to Lucky Gunner for providing PMC brand rifle ammunition.