Welcome, everyone! If you’re viewing this article you likely have a few questions about the different kinds of firearm cartridges that can be found out in the wild.
It can be an intimidating topic for newer gun enthusiasts as there are hundreds of different options and it can be pretty overwhelming to take it all in.
Luckily, I have created this easy-to-digest post about the topic and in the end, you will come out with a wealth of new knowledge about all things bullets.
Common Bullet Types
The bullet is the part of the cartridge that gets so excited when the firing pin hits the primer that it will spring out of the barrel as fast as possible to go and greet your target.
Let’s go over the most commonly found types.
Full Metal Jacket
Known as FMJ for short, full metal jacket rounds are going to be the most common you find for sale. FMJ bullets will usually have a lead core with a tougher metal casing.
They can have a rounded or flat tip and they feed more reliability into the firearm than some other bullet variants.
FMJ ammo tends to be able to penetrate deeper than other types which can lead to overpenetration in defensive firearms use making them not as recommended as things like hollow points.
Known as HP for short, as you can likely predict these bullets have an indent on the tip of the projectile. A standard hollow point bullet is created with a soft material (again usually lead).
The major draw to this bullet style is that upon collision a hollow point will rapidly expand releasing major energy on the impacted target. This energy transfer also makes overpenetration much less likely compared to FMJ ammo.
Jacketed Hollow Point
JHP bullets are very similar to the above-mentioned hollow points but they also have a hard outer casing like FMJ rounds.
The indented tip may or may not be fully jacketed. These rounds are usually designed for defensive purposes and every company has a different perspective on what is the ideal way to manufacture their bullets.
Combining the features of the FMJ and HP bullets creates a round that distributes great stopping power while being able to control the expansion and manage the mushrooming effect when the target is hit.
Semi-Jacketed Hollow Point
Very similar to the JHPs, Semi-Jacketed Hollow Points (SJHP) ammo combines a jacket with a hollow point but the jacket will not completely cover the entire projectile.
This type of ammunition is most commonly found in revolver rounds.
SJHPs allow the bullets to penetrate deeper than a typical hollow point and still distribute tremendous force on the target by allowing the bullet to mushroom larger than a fully jacketed hollow point.
Soft point (SP) rounds are most commonly found as hunting ammunition and are also referred to as soft nose by some.
These bullets will have a semi-jacketed projectile with a rounded exposed tip. This is perfect for hunting purposes since the design is capable of piercing thicker hides while also being able to distribute a lot of force on impact.
Although they may seem a bit strange at first, wadcutters serve a very specific purpose. A wadcutter is unjacketed and is flush fitting with the cartridge case and is excellent for target shooting.
There is nothing that punches paper cleaner than a wadcutter. It honestly looks like you walked up to the target with a hole punch and used it on the target. I find these perfect holes very satisfying to look at and they are easier to see than holes made with FMJ target ammo.
Semi-Wadcutter & Truncated Cone
Both of these are similar. They feature a flat nose and can be found jacketed, semi jacket, and hollow point.
The difference between the two is that the semi-wadcutter will also have a flat ring around the bullet close to the casing as well. Whereas the truncated cone will gradually taper down the full length of the exposed part of the bullet.
With the rise of technology, we have gained a new way to throw our hollow points down range, by putting a polymer tip on them.
The advantage to this is that the ballistic tip keeps the trajectory of the bullet true to the flight path without as much drag while still being able to solidly impact a target.
Premium hunting ammunition has these types of bullets, especially those that are catered toward the longer-distance shooting.
Armor Piercing & Steel Core
If your ammo is coming from a can, wrapped in cardboard-like above, or has a painted tip or base of the bullet there is a good chance that you are dealing with a reinforced core.
AP rounds will have a steel or other heavy alloy core in the projectile in the hopes to defeat body armor or other materials depending on the size of the bullet.
Can citizens own steel core ammunition in the United States?
The answer is yes. Ammunition manufacturers create millions of rounds for military purposes every year but sometimes the batch does not meet military specifications. This ammo is then diverted to civilian sales.
Does this mean that the ammunition is unsafe?
No, the military has strict requirements for its ammunition. Some problems can be very minor and not even affect a whole manufactured batch but as long as they meet commercial requirements they would rather send it to the civilian market than take a loss on the product.
And we the consumers have no problem with taking that extra ammo off their hands.
I have personally used and have observed tens of thousands of “XM” (as in it does not meet military specifications) fly downrange and rarely saw any issues.
That being said a lot of surplus ammunition is also steel core and it can be difficult to determine if it is or not.
Many ranges ban the use of any type of armor-piercing/ steel core ammunition since it can severely damage their backstops.
We’ve been talking a lot about bullet tips but did you know that the other end also matters?
Enter the boat tail (BT). This tapered boat shape added to the end of the bullet hidden by the cartridge casing can help stabilize the projectile and allow it to more accurately engage targets out to longer ranges.
It is most common to find these on rifle rounds either on FMJs, JHPs, and Ballistic Tips.
Regardless if you are just target shooting, hunting, or competing these kinds of bullets will aid your bullet stability.
What Does Caliber Mean?
The caliber is the diameter of the gun barrel usually measured in either inches or millimeters (mm). This is also referred to as the gun bore.
The Difference Between Centerfire and Rimfire
The major difference between the two types of cartridges is the placement of the primer.
On a centerfire cartridge, the primer is inserted in the middle of the bottom of the casing.
A rimfire cartridge has the primer located inside the rim of the bottom of the casing.
You can visually see the primer when looking at the bottom of a centerfire cartridge but for a rimfire, the primer is built-in and cannot be seen from the outside.
There is no “right” position for the firing pin to impact a rimfire case. The primer exists in a ring around the rim of the case.
Other Pieces of the Cartridge
Now that we started to talk about other parts of the cartridge as a whole, let’s explore them all. Don’t worry it’s not too complex and most of the components have already been mentioned.
The case is the piece that holds all the components together. The bottom is where the primer can be found. It is filled with the propellant and the projectile is firmly placed in the opening sealing it shut.
This creates the perfect place for rapid gas expansion allowing the projectile to fly quickly out of the barrel.
Everything we have discussed so far today revolves around smokeless powder. This is modern gunpowder that is less volatile than traditional black powder and does not make nearly as much smoke, as its name suggests.
Gun powder in itself can be a very deep topic on its own but I will skim the basics.
It is measured in grains and even within the subcategory of smokeless powder, there are dozens if not hundreds of different kinds of powder.
Some burn faster than others and they even come in different shapes, sizes, and colors.
The primer is the piece that is struck by the firing pin and ignites the propellant. As mentioned before there are centerfire and rimfire cartridges that both have different primer locations.
But did you know that centerfire cartridges can also have different types of primers? The most common today are Boxer and Berdan primers. If you ever plan on getting into reloading, boxer primers are going to be what you are going to use 99 percent of the time and it’s what the majority of major ammunition manufacturers use as well.
Similar to the propellant, primers also come in different sizes to best fit the caliber of the cartridge.
So if you are even considering learning to make your own ammo, saving your spent brass casings is a great way to start your case collection.
Let’s start with the smallest and one of the most popular. This caliber is perfect for a first-time shooter, you can find it in rifles and handguns. It is cheap and plentiful to find and the recoil is nearly non-existent.
The only main downside to this caliber is that it does tend to jam more due to the rimfire design and some ammo can be pretty dirty, requiring more frequent cleaning.
There are multiple .22 calibers but .22LR is by far the most common. .22 Short and .22 Long are other calibers that can safely fire from some bolt action .22LR rifles. One other decently popular one is .22 Magnum. This is its own caliber with a slightly wider bullet so make sure you keep them separated from your other .22 ammo.
The most popular handgun round is the 9×19, 9mm parabellum, 9mm Luger (all the same). When someone refers to 9mm they are likely talking about this caliber.
This is a great choice for a fire centerfire cartridge. Ammo is plentiful and cheaper than a lot of other options. With pistol caliber carbines being a thing you don’t need to stick with only handguns in this flavor either. Recoil is very manageable and you are given a wealth of different gun options to choose from.
One thing I would ask you to be careful of if you are new to shooting is that other 9mm calibers are not as popular and these rounds are not interchangeable. If you are unsure what the caliber is in what you are looking to buy, there is no harm in asking.
.40 Smith & Wesson
.40 S&W for short. This is the one to pick if you want a fast-moving bullet like a 9mm but you want it to be big like a .45.
This caliber was all the rage with police and saw widespread adaptation across the world due to it being a large fast round.
Ammo won’t cost you much more than 9mm and is pretty easy to source.
One thing to note though this is a snappy round and will have noticeably more recoil than the previously mentioned options.
A classic big-bore round. When you think of this round your mind probably goes to the 1911, a classic in its own right as well.
This round was created back in 1904 by John Moses Browning himself and has had a legacy of military service ever since.
Rounds are a bit pricer than the previous offerings but still not unreasonable. Although this is a big bullet, it does have manageable recoil since it is slow-moving.
.357 Magnum and .38 Special
Note the +P designation on this box of ammo. When you see this it means that there is more powder in this ammunition than in a regularly loaded 38 Special round. This means more stopping power and more recoil. Be careful though as some older guns were not made with these higher pressures in mind and they may not handle them well.
Continuing along the trail of time-honored calibers we have some legendary revolver rounds.
The 357 Magnum is a powerhouse that slings a bullet about the same diameter but with more mass than a 9mm downrange at even faster speeds.
38 Special on the other hand is a 357 with a smaller case length and therefore less powder and pop.
Although I wouldn’t necessarily recommend the 357 magnums to an inexperienced shooter, 38 special is a beauty for trying out revolvers for the first time. The best part is if you purchase a 357 Magnum revolver it can fire both rounds!
Note that it does not work the other way around.
Not only that but 38 special was the first centerfire caliber that I shot in a handgun through an old Smith and Wesson 686.
.223 Rem & 5.56 NATO
Here is some of that XM ammunition that I spoke about earlier.
Time for another conversion round of sorts.
The 223 and 556 rounds are nearly identical but with one major difference. 5.56 has much higher case pressures.
Because of this, you can safely fire a 223 round out of a 5.56 rifle but you cannot do the opposite.
Both of these rifle rounds are extremely popular. You will end up paying a bit more for the same amount of pistol rounds but they are still very reasonable compared to other rifle rounds.
You will have a lot of fun at the range with a 223 or 5.56 rifle whether it’s a bolt action or a semi. It makes some noise, has little recoil, and can reach out to a decent range without much issue.
7.62 x 51 & .308 Winchester
Going further along the NATO rifle offerings is their .30 caliber round, the 7.62 x 51. Similar to how .223 and 5.56 are pretty much identical except for the military round having higher case pressure these two calibers have the opposite outcome.
The civilian .308 Win rounds are higher pressure and can handle the 7.62 rounds but guns only rated for the NATO rounds will not be able to handle .308 pressures.
This is not as hard a rule as with the smaller caliber example before as it does not enter the unsafe zone according to SAMMI but I probably wouldn’t risk damaging an M1A by testing if it would be okay with using out of spec ammo.
7.62 x 39
Another 7.62 rifle? Yupp, not only that but there are MANY 7.62 calibers but this one is different from the next most popular one.
This caliber is found on many Russian rifles and derivatives. Things like the SKS and AKMs quickly come to mind.
These intermediate cartridges are noticeably larger than the 5.56 counterparts but are also smaller than the 7.62 x 51.
Recoil is very manageable and it’s a fun round to use.
It can be harder to find ammo for this caliber now, unfortunately. In the past, you couldn’t go to your gun store without tripping over a crate of old surplus ammo.
Time for Something a Little Different… Shotguns
You may have guessed it but shotguns don’t play by all the same rules as rifle and handgun rounds.
Not only that but shotguns give the shooter a lot of variety in what kind of rounds they can put through their gun so let’s go through the options.
7.5 and 8s are great for target shooting
Birdshot consists of many small ball projectiles that will disperse and hit a wide pattern.
This is optimal for bird hunting as it gives the hunter some grace in a potential hit since some birds can move through your field of fire in a fraction of a second.
The shot comes commonly in lead or steel. Lead rounds are cheaper and used very commonly for skeet, trap, and just general target shooting. Reduced recoil target loads are even offered to take away a lot of the recoil that is associated with larger bore shotguns.
While some species allow for lead shot to be used while hunting, many places require a hunter to use steel or other alternatives that won’t contaminate the wetlands.
Birdshot comes in a variety of sizes to cater to what you may be hunting.
Buckshot is great, it can be used for hunting, fun for the range, or as an excellent option for home defense.
Similar to birdshot, there is a variety of different size “shot” that buckshot can come in. The most common being 00 (double-aught) buck.
The recoil on buckshot will be noticeably harder than many birdshot options, although reduced recoil loads are also available to play around with.
Now, what if we decided instead of having any projectiles we just stick one giant hunk of lead down the shell and called it a day?
Enter the slug.
Slugs come in two kinds, rifled and sabot. Rifled slugs are used in smoothbore barrels. They have wings that will stabilize the slug to be able to make fairly accurate shots out to ranges that would not be as accommodating for buckshot.
Sabots on the other hand are made to be used with rifled shotguns (yes that is a thing) They are popular with hunters and have smooth sides that will allow the rifling of the barrel to make the projectile spin resulting in even more accurately placed shots over rifled slugs.
A Few Other Differences
Multiple Shell Lengths
Another way that shotguns give shooters versatility is that they can utilize multiple shell lengths.
For example, for 12 gauge shotguns, most modern shotguns will allow 2 ¾ inch shells and 3-inch shells. While some shotguns will also accommodate 3 ½ inch shells… that’s a lot of mass heading downrange with the recoil to match.
Always check your shotgun for shell compatibility to make sure what you are loading can be handled by the firearm.
An Extra Component
To keep the shot contained and traveling the direction you want an extra component to the shell needs to be added that is not found on a rifle or pistol cartridge.
A plastic wad separates the propellant from the projectile(s) that also travels out of the shotgun along with the payload.
How is a Gauge Measured?
Okay, this is an interesting fact that even a lot of seasoned firearms enthusiasts don’t know the answer to.
Before the early 19th century there wasn’t a standardized unit to measure the thickness and diameter of an object.
It goes without saying that when dealing with explosive powders and projectiles moving at thousands of feet per second, being precise is something you should pay particular attention to.
Enter the introduction of the gauge measurement. By taking lead cylinders of similar size and comparing how many of the cylinders it takes to make a pound’s worth of those cylinders, gunsmiths were able to create a system to accurately determine the bore of the shotguns of the day.
So taking a 12 gauge shotgun, for example, the bore diameter of the barrel fits a twelfth-pound lead cylinder.
And now we are at the end of the road. Did you learn anything? I bet it was the gauge measurement thing.
I hope that you enjoyed our article and it was informative.
I love being able to use my experience to help new shooters and this is a great way for me to reach them.
If you know someone who is wanting to get into shooting send them this link and they will come out of it better equipped when they decide to take the jump into the world of gun ownership.
Until next time this is Phillip, signing off.