Firearm Universe

The Ultimate Ammo Guide – Find the Right Cartridge for Every Application

It’s one thing to sift through the product pages of your trusted online firearm dealer to find the gun you need, and quite another to decide what kind of ammunition to put in it. It seems every weapon needs a different cartridge for every shooting application and finding the right one is a journey down a path that ends up littered with empty brass casings and an even emptier wallet. That’s why it is essential to narrow down the choices up front, so you can spend more time hunting or enjoying the shooting sports, and less time working to pay for ammo that was nowhere near on target. Ammunition is a vast world of caliber, grain, and bullet types that leave even the most seasoned gun connoisseur in a fog of confusion. Let’s tackle this world head-on and see if we can figure out what rounds are going into your magazine, once and for all.

The Composition of a Cartridge

In the firearm world, “caliber” means the diameter of the barrel and the diameter of the bullet that is going through it. A “bullet” is simply a metal projectile, and this fits neatly along with powder and a primer in a thing called a cartridge.

In ammo-speak, a .38 bullet is .38-inch in diameter, and a 9mm is nine millimeters wide. Size wise, a 9×19 cartridge is considered nine millimeters wide by 19 millimeters long, and a 5.56 X 45mm rifle round would be 5.56mm wide by 45mm long, and so on.

There are two types of cartridges, rimfire, and centerfire. In a centerfire round, the primer sits in the center of the cartridge, and in a rimfire, the primer runs around the rim cavity. The firing pin strikes the primer and ignites the propellant, causing an explosion which expels the bullet from the casing. In a rimfire, which is the least expensive of the two, the firing pin strikes only one point of contact on the rim, accomplishing the goal of gunpowder ignition.

Separating the Wheat From the Chaff on Grain

Grain is a unit of measurement from the Bronze Age that describes the bullet’s weight, not the weight of the powder in the cartridge, and is nominally based on the mass of a single grain of wheat or barley. In today’s world, it is agreed that 7000 grains equal 1 pound, and in ammo-land, higher grain weight means a heavier bullet.

In general, the heavier grain bullet will hold its energy, penetrate deeper and drift less in the wind but is prone to a faster drop. Lighter grains move faster and stay flatter than a heavier grain bullet but may not penetrate as well due to less mass. A general rule is the bigger the desired target, the heavier the grain. Because each shooter, firearm, and application are different, trial and error on the range is the only way to be sure you have the right grain for your scenario.

The Basics of a Bullet

  • Soft Point or SP/JSP – A soft-point bullet is a soft metal core surrounded by a durable metal jacket that’s left open at the tip and is designed to expand upon impact. The soft point flattens upon hitting the target and generally isn’t the first choice of hunters because of the need to penetrate game for a decent killing shot.
  • Hollow Point or HP – This projectile also expands and is best suited for situations that require controlled penetration, where the desired outcome is a bullet that stops the assailant but does not go beyond and cause injury to others. They have excellent stopping power and are used by police officers and the like, as well as aboard aircraft and in other highly populated places.
  • Ballistic Tip or plastic tipped – Most often the round of choice for hunters, this bullet is much like a hollow point that is filled with hard plastic. This construction makes the projectile streamlined and offers greater penetration before the lead expands. They are known for longer trajectory and improved accuracy which is essential in big game hunting.
  • Open Tip Match or OTM – This bullet is used by the military but not by most civilian hunters. It is incredibly accurate due to its nearly perfect weight distribution and design, so it is mostly used as target shooting ammo or in competition.
  • Full Metal Jacket or FMJ – Made famous by the 1987 film that shares its name, this bullet is lead surrounded by a jacket of hard metal. Its design prevents excessive depositing of metal in the bore thus averting damage to the weapon and allows for smoother feeding of ammo into the firearm.

A Compilation of Calibers

Here is a run-down of a few of the most common calibers available and their uses. As a reminder, always, always stay with the caliber cartridge your weapon specifies. Some guns can shoot different rounds but to be safe, always consult the manufacturer’s instructions on what your firearm is engineered to handle.

  • .22LR – Probably the most commonly known caliber in the world and the victim of occasional ammunition shortages, the .22 Long Rifle is the go-to round for varmint and small game or target shooting.
  • .380 ACP – Here’s where the cut-off is for a caliber that has “assailant-stopping” power. The .380 produces minimal recoil and is generally the lowest caliber recommended for self-defense.
  • 9mm – This German-inspired cartridge is by far the most popular for military and law enforcement personnel. Most of us have or know someone who has a “9 mil” pistol. The sheer availability of handguns in this caliber makes it ideal for home defense or personal protection. Interestingly, the 9mm bullet is the same diameter as the .380, but the 9mm casing and overall length are longer resulting in slightly more power and recoil.
  • .40 S&W – Invented by John Browning, this caliber was used extensively by the FBI and is more powerful than the 9mm. The .40 is considered an excellent choice for a dependable and commanding sidearm.
  • .44 Magnum – This round was made famous by Clint Eastwood in the 1971 film, Dirty Harry. Powerful? Yes. The most powerful in the world? Sorry Mr. Callahan, but no, the .500 Smith & Wesson Magnum now holds that title along with a handful of other similar calibers.
  • .45 ACP – The military has their name written all over this cartridge, as it has a long history in the armed forces. It’s a heavy bullet that produces just as heavy recoil and the firearm availability in this caliber is plentiful.
  • .38 – A revolver round, the .38 is slightly longer and heavier than the 9mm, and the .38 Special is the same diameter as the next caliber on the list. This ammunition has the power to stop an attack with a manageable recoil that’s not out of hand.
  • .357 – Here comes one of the big boys, and this revolver round is best suited for house guns and fending off dangerous game. Some revolvers, like the Smith and Wesson Model 66 fire both .357 and .38 special.
  • 224 Valkyrie – Born from a 6.8 SPC casing modified to accept .224 caliber bullets, the Valkyrie is referred to as a “supersonic” cartridge that’s similar in size to a
  • 5.56X45MM/.223 – This cartridge was developed by FN Herstal in the late 1970s and inspired by the .223 Remington. Both projectiles in these rounds have nearly the same dimensions, and the .223 Remington can be used in a 5.56 rifle. However, rifles of the AR variety will specify either .223 Remington, .223 Wylde, 223 Noveske or 5.56×45mm NATO chambers.
  • .308 / 7.62x51mm – Here’s another hunting round that has the same bullet diameter as those used in AR type rifles. According to the NRA, a .308 Win chamber can handle both .308 Win and 7.62 NATO ammo safely, but if you have a rifle marked for 7.62 NATO ammo, it’s best to use only that.
  • 6.5 Creedmoor – Based on the .308, this rifle cartridge developed by Hornady in 2007 is ideal for long-range target shooting and hunting applications. It boasts a flatter trajectory, better long-distance knock-down power and less felt recoil than the .308, making it a popular load for wild game like whitetail deer.
  • 300 Blackout – There’s a lot of chatter about the Blackout in the AR domain because it is designed to provide the ballistic performance of the AK 7.62x39mm round in an AR-15 with standard magazines. It is becoming the go-to cartridge for shooting out of short barreled rifles with suppressors.
  • .30-06 Springfield – The “thirty-aught-six” was created in 1906 and was the most popular military cartridge for around 50 years before being replaced by the 7.62×51mm NATO (.308 Winchester) and the 5.56×45mm NATO (.223 Remington.) These replacements are still in service with U.S. and NATO forces. Its name is infamous, and many a hunter speak fondly of their old reliable “aught-six.” Interestingly, the “.30” refers to the caliber of the bullet and the “06” refers to the year the cartridge was invented.
  • 350 Legend – Hot off the ammo press is this straight-walled cartridge that features around 20% less recoil than the .243 Win with 20% more penetration, which makes it an ideal cartridge for young hunters who might shy away from the shoulder shock of a typical long rifle. Bullet size on this round is .357 of an inch in diameter, and its straight-wall design makes it legal for use in some states that traditionally only allowed deer hunting with a shotgun, muzzleloader or handgun.

And for those wondering what that +P means on a box of ammo, in general, over pressurized or +P is ammo manufactured with a higher pressure than a standard cartridge which results in faster muzzle velocity and boasts greater penetration than unpressurized rounds.

The Hunter’s Caliber Conundrum

For hunters, it is imperative to know which caliber to use for the quarry they chase to ensure quick and efficient knock-down and clean kills. According to the experts, here are the calibers used for each type of game.

  • Small game at short to medium range – .17 HMR, .22 Hornet, .22 LR, .223 REM.
  • Predators at long range – .223REM, .22-250 REM, .220 SWIFT,.243 WIN.
  • Deer at short range – .243 WIN, .30-30 WIN, .300 SAVAGE.
  • Black Bear at short range – .30-30 WIN, .300 SAVAGE.
  • Deer, Black Bear, Caribou, Sheep, Elk, and Hog at medium to long range – .270 WIN, .308 WIN, .30-06 SPRINGFIELD, 7mm REM MAG, .300 WIN MAG.
  • Grizzly, Brown Bear or Moose – .300 WIN MAG, .300 WBV, .338 WIN MAG, .375 H&H.
  • Alternative for Black Bear – .444 MARLIN, .45-70 GOVT.

So, What Do You Use for Personal Defense?

For concealed carry or home defense, the name of the game is stopping power. You need a bullet that penetrates well but does not travel through the assailant and into innocent bystanders. Ammunition manufacturers have combined the penetration of a full metal jacket and the expansion of an all lead bullet into ammo that has the stopping power needed without overpenetration of the target. This design is known as the bonded jacketed hollow point or JHP, and manufacturers usually label this ammo “personal defense” or some other such jargon to indicate its intended use.

Also, there are cartridges engineered to be used in close quarters, retail stores, apartment buildings, and by sky marshalls aboard airplanes. Called Glaser Safety Slugs, these rounds are for unobstructed, close-range self-defense in locations where any overpenetration would be devastating, such as inside of an aircraft.

Choosing ammunition isn’t like it used to be, that’s for sure. The calibers are vast, bullets are varied, and the choices in grains are endless. You can research these things “till you’re blue in the face,” but finding the right ammunition still boils down to narrowing your choices to a couple of types, heading out to the range and slinging lead until you are happy with the results. Hopefully, those results are accurate, with enough precision and stopping power you need to halt an aggressor or take down that 180-class Boone and Crocket buck on the first shot.

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