The AR rifle platform is a favorite for many American shooters because it's versatile and available in a number of calibers and cartridges useful for target shooting, home defense and hunting.

You can cover the spectrum with an AR, but that begs the question: What's the best AR caliber or cartridge for your situation?

In this article, we list the best AR calibers & cartridges available in 2025 and why they work well whether you're taking an AR to the range, hunting, or defending your home.

If you can't wait, the 22 Long Rifle (22 LR) tops this list. If you want to see the full AR caliber list, keep scrolling.

Shop 22 Long Rifle Ammo

My Top 6 AR-15 Caliber Picks

Here are our favorite AR-15 caliber choices:

1. .22 Cal
2. 6.8 SPC - Best AR-15 Caliber for Home Defense
3. 6.5 Grendel - Best AR-15 Caliber for Long Range
4. .30 Cal
5. .355 Cal / 9mm
6. .45 Cal

Let's examine each AR caliber and cartridge in depth to help you choose the best one for your shooting needs.

Testing Procedure

I considered many factors while choosing the best AR calibers and cartridges for this list, including (but not limited to):

• What was the cartridge designed for?
• Ballistic performance
• Price
• Functionality

Understanding why the cartridge was created and how it fits into the AR platform is the best way to choose the one that suits your preferences.

How the cartridge performs ballistically is another key factor you must consider. A long-range cartridge is great for target shooting but will be impractical for home defense.

All of us are on some sort of budget. Just as many of us want ammo that will stay within that budget's confines – without forfeiting reliability.

Lastly, if the cartridge doesn't function well in the AR platform, it shouldn't be on the following list. I rounded up cartridges that have proven to function reliably in the AR platform.

My Top 11 AR-15 Cartridge Picks



22 LR - Best All Around AR Cartridge



Shop 22 Long Rifle Ammo

Pros & Cons

Pros

• Low recoil
• Inexpensive
• Cheap & easy conversion

Cons

• Only good for hunting small game and target shooting
• Limited effective range
• Rimfire primers are inherently less reliable than centerfire ones

Why I Chose It

If you're like me, the first shot you ever fired was with a .22 LR rifle. As the most popular round on the planet, the .22 LR is unquestionably the best AR round thanks to its negligible recoil, extremely low cost, and high availability.

The greatest benefit of the .22 LR in an AR-15 platform is that it allows you to train with your standard 5.56 NATO rifle for a fraction of the cost. Converting an AR-15 to 22 LR only requires a conversion bolt and new magazines, as any AR 5.56 barrel can safely handle 22 LR. It's much easier than converting an AR to a cartridge of a different caliber, as doing so requires a new barrel.

AR-15 22 LR conversion bolts and magazines are inexpensive, and 22 LR bulk ammo is dirt cheap and fun to fire. You can spend a day firing 500 rounds of 22 LR for approximately one-fifth the cost of the same amount of bulk 5.56.

6.8 SPC - Best AR-15 Cartridge for Home Defense



Shop 6.8 SPC Ammo

Pros & Cons

Pros

• Designed for CQB
• Suitable for medium game hunting within 200 yards
• High striking energy compared to 5.56 NATO

Cons

• Fewer options
• Relatively expensive

Why I Chose It

The 6.8 SPC makes an excellent choice for home defense, as it was developed specifically for close-quarters and mid-distance combat and has exceptional short-range terminal ballistics.

Developed in 2004 as a joint operation between Remington Arms, U.S. Special Operations Command (USSOCOM), and the U.S. Army Marksmanship Unit (USAMU), the 6.8mm Remington Special Purpose Cartridge (SPC) was designed to improve the terminal performance of the M4 carbine.

The program aimed to produce a cartridge that mimics the stopping power of the 7.62x39mm. In general, the 6.8 SPC was successful at accomplishing this task. However, due to chamber design issues when Remington first presented their new round, the 6.8 SPC was not adopted by the Armed Forces.

The U.S. military may have passed on the 6.8 SPC, but that doesn't mean it's ineffective. On the contrary, the 6.8 SPC is an especially potent short-range cartridge, boasting a 45% increase in muzzle energy compared to a standard 5.56 NATO M855 load.

Its added kinetic energy makes the 6.8 SPC an excellent choice for a home defense carbine. It is also popular for hunting deer and hog within 200 yards.

6.5 Grendel - Best AR-15 Cartridge for Long-Range



Shop 6.5mm Grendel Ammo

Pros & Cons

Pros

• Designed for long-range
• High ballistic coefficient
• Flat trajectory

Cons

• Relatively expensive
• Fewer options

Why I Chose It

The 6.5 Grendel is an excellent long-range cartridge for the AR-15, as it fires a bullet with a high ballistic coefficient and resultant flat trajectory.

Although it took a little while for the 6.5mm bullet to take hold here in North America, long-distance shooters have become keenly aware of its long-range accuracy over recent years. Its relatively sleek profile stirs up very little drag in flight, which helps to flatten trajectory, diminish wind interference, and increase downrange striking energy.

The 6.5 Grendel was conceived as an intermediate cartridge that would extend the effective range of AR-15 rifles beyond 800 yards. Utilizing the same higher-ballistic coefficient 0.264" diameter bullet as the 6.5 Creedmoor, the 6.5 Grendel can maintain MOA accuracy and supersonic velocities out to 1,200 yards with half the recoil of the 308 Winchester.

6.5 Creedmoor - Most Accurate AR Caliber



Shop 6.5mm Creedmoor Ammo

Pros & Cons

Pros

• Very accurate, even at long distances
• Flat trajectory
• Can be used for big game hunting

Cons

• Less powerful than other big game cartridgesWhy I Chose It

If you don't mind stepping up to a larger and heftier AR-10 rifle, then you can witness the dramatically improved ballistic performance of the 6.5 Creedmoor. The round is highly popular among competitive long-distance shooters, whom it was designed for.

When I first fired the 6.5 Creedmoor, I had two immediate reactions. "That was fun!" and "That's surprisingly low recoil!"

The 6.5 Creedmoor single-handedly started the lovefest currently centered around 6.5mm bullets here in North America. Introduced by Hornady in 2007, the 6.5 Creedmoor was co-developed by renowned marksman Dennis DeMille and Hornady senior ballistician Dave Emary.

The two created a cartridge with low recoil, a flatter trajectory than the 308 Win, and relatively accessible 1,000-yard shots. Extremely tight tolerances in the chamber throat design make the Creedmoor one of the most inherently accurate out-of-the-box rounds on the market.

Combining the accuracy and lower recoil of the 6.5 Creedmoor with the semi-automatic capability of the AR-10 makes for a potent long-range target rifle.

300 AAC Blackout - Best AR Pistol/SBR Caliber



Shop 300 AAC Blackout Ammo

Pros & Cons

Pros

• Low recoil
• Abundant ammo selection
• Designed to perform well with short barrel

Cons

• New barrel needed for conversion from 5.56 NATO

Why I Chose It

If you're looking to build or buy an AR pistol and want a cartridge that delivers optimal performance out of a short barrel, look no further than the 300 AAC Blackout. Thanks to its lower recoil, it's one of my favorite cartridges. It's perfect for lightweight AR-15s.

The 300 Black increases the caliber of the AR-15 rifle to 0.308". Put simply, the 300 BLK is a 223 Rem case that has had its mouth widened to seat a .30 cal bullet. This allows the 300 BLK to fit in standard AR mags and maintain their normal 30-round capacity. It also means that you don't have to purchase a new bolt to fire 300 Blackout, as the base diameter of the case is unchanged from 5.56. Although the mags and bolt remain unchanged from a standard AR-15, a new barrel is
required to perform a conversion.

Robert Silvers and Advanced Armament Company (later acquired by Remington) designed the 300 Blackout to achieve full powder burn in a 9-inch barrel, which is why it's so often favored for short-barreled rifle (SBR) and AR pistol builds. The 300 BLK is available in supersonic and subsonic factory loads, making it extremely versatile.

Supersonic loads work well for target shooting, long-range engagements, and whitetail hunting. Subsonic rounds are ideal for use with a suppressor, giving them excellent short-range stopping power accompanied by a report that won't deafen you indoors.

6mm ARC - Best Overall AR Caliber For Hunting



Pros & Cons

Pros

• Better ballistics than the 6.5 Grendel
• Small and medium game animals aren't safe

Cons

• Not designed for big game
• Less available than other cartridges
• Not taking off like Hornady had hoped

Why I Chose It

A relative newcomer to the shooting scene, the 6mm ARC cartridge fires a 0.243" diameter bullet that is effective on varmints, antelope, coyotes, and whitetail deer. It covers a wide breadth of hunting capabilities, which makes it the best multipurpose AR-15 hunting cartridge on the market.

The 6mm Advanced Rifle Cartridge (ARC) was introduced by Hornady in 2020, making it the youngest round on our top 11 list. It was developed at the behest of the U.S. Department of Defense for its multipurpose combat rifle program. Designed by necking down a 6.5 Grendel case to accept a 6mm bullet, the 6mm ARC requires a new bolt, barrel, and magazine to convert a standard .22 cal AR-15.

The 6mm ARC provides shooters with improved ballistics over the 6.5 Grendel, mostly due to its higher muzzle velocity. Capable of launching a 103 grain ELD-X at a velocity of 2,800 fps (with 1,792 ft-lbs of muzzle energy), the 6mm ARC is a flat-shooting, hard-hitting round that is more than capable of dispatching virtually any North American game (short of great bears and elk). Groundhogs, coyotes, and deer stand no chance against this hotrod, making it a jack-of-all-trades hunting cartridge that mimics the 243 Winchester in an accessible AR platform.

22 Nosler - Best AR Cartridge for Varmint Hunting



Pros & Cons

Pros

• Lower recoil
• Flat trajectory
• High muzzle velocity

Cons

• 22-250 ballistics are often better
• Unpopular; difficult to find

Why I Chose It

The 22 Nosler makes an amazing choice for varmint hunting due to its high velocity, flat trajectory, and lower recoil compared to other intermediate cartridges.

Ever wonder what it would be like to get 22-250 Remington velocities out of a standard AR-15? The 22 Nosler nearly accomplishes this thanks to its 25% increase in case capacity over 5.56 NATO. According to Nosler's website, this increase produces 14% higher muzzle velocity and a 30% increase in kinetic energy.

You will need a new barrel for the 22 Nosler. But thanks to its rebated rim, it is compatible with a standard AR-15 bolt.

Debuted at SHOT Show 2017, the 22 Nosler was the fastest AR-15 cartridge of its time, boasting velocities normally reserved for bolt-action cartridges like the 220 Swift and 22-250 Rem. To put this into perspective, a 22 Nosler can launch a 55 grain projectile at 3,500 fps – not far off of the 22-250, which commonly hits a muzzle velocity of 3,680 fps.

For varmint hunting, lightweight projectiles and high muzzle velocities are preferred. The 22 Nosler delivers both in spades.

308 Winchester - Best Cartridge for Big Game Hunting



Shop 308 Winchester Ammo

Pros & Cons

Pros

• Time tested
• Flat trajectory
• Plenty of stopping power for big game

Cons

• Surpassed in performance by more modern rounds
• Not suitable for dangerous game

Why I Chose It

The tried-and-true 308 Winchester is virtually identical to the 7.62x51mm – the very same cartridge the AR-10 was designed around. A 308 Win AR-10 is an excellent tool for taking down whitetail, black bears, and even the mighty elk. My dad used a 308 Win to take his first elk without a problem, and I wouldn't hesitate to take a 308 Win rifle big game hunting anywhere in North America.

Developed in the 1950s to replace the aging 30-06 Springfield, the 308 Winchester has remained the go-to round for designated marksmen, snipers, and machine gunners since its release. The 308 Win has also cut its teeth in the backwoods, and is the favored large game hunting cartridge among many outdoorsmen.

With seemingly unending bullet and load variations, there is a 308 Win cartridge for every
possible hunting scenario. It is my pick for the best big game hunting cartridge for an AR-10 rifle.

450 Bushmaster - Best AR-15 Cartridge for Whitetail



Pros & Cons

Pros

• Legal in straight-walled cartridge only states
• SAAMI-certified
• Plenty of stopping power for whitetail deer

Cons

• It's a shoulder thumper
• Relatively limited selection

Why I Chose It

If you want to go deer hunting and plan on firing an AR-15, then the 450 Bushmaster's superior stopping power, range, and bullet selection will all prove great companions on your journey.

The 450 Bushmaster is what Lt. Col. Jeff Cooper referred to as a "thumper round." Such cartridges are larger than 40 caliber, and more than capable of taking down a whitetail deer in a single shot from an AR-15.

Thumper rounds get their name from the sensation you feel in your shoulder upon firing them. In other words, they are all high-recoil cartridges.

Developed for deer hunting across multiple states and territories, the 450 Bushmaster uses a straight-walled case that complies with hunting ammo restrictions in several Midwest states including Indiana, Michigan and Illinois.

The 450 Bushmaster is manufactured by multiple companies. It's not ubiquitous, but it is readily available. It is also the only thumper round on this list that is SAAMI certified. For conversion, you'll need a new barrel, bolt, and single-stack magazine follower (the 450 Bushmaster can utilize standard AR magazines so long as the follower is replaced).

Once it has pushed a 250 grain SST to a muzzle velocity of 2,200 fps with 2,700 ft-lbs of accompanying kinetic energy, the 450 Bushmaster is more than capable of taking down a whitetail within 200-250 yards, thus making it your choice for deer hunting with an AR-15.

458 SOCOM - Best AR Cartridge for Hog Hunting



Pros & Cons

Pros

• Fast follow-up shots
• Plenty of stopping power

Cons

• Fewer options
• Expensive
• Not SAAMI certified

Why I Chose It

The 458 SOCOM is another thumper round that makes an excellent hog-hunting cartridge. Its high muzzle energy and fast follow-up shot capability make it ideal for this task. The 458 has also made a name for itself among whitetail and elk hunters, but hog hunting is where it really shines.

The ability to take fast follow-up shots with a hard-hitting round like the 458 makes it perfect for engaging multiple targets, or making second shots on tough game (like hogs). Feral pigs have become an inordinately large problem in the Southern United States, where herds frequently destroy farmland and landscaping. More than a few golf courses have been ruined by roving bands of swine as well.

Ammo availability is one of the few downsides to the 458 SOCOM. Handloading easily remedies this problem, as multiple manufacturers offer 458 SOCOM component bullets (such as the show-stopping 300 grain TTSX by Barnes).

Like the 450 Bushmaster, converting from 5.56x45 to 458 SOCOM requires a new bolt, barrel, and single-stack magazine follower. The 458 SOCOM's bottlenecked design allows for more reliable feeding and higher case capacity than straight-walled cartridges of similar size.

The 458 SOCOM is exceptionally effective for self-defense. Take care that close-range shots could result in over-penetration. Although expanding bullets cannot eliminate this risk, they do reduce it, which is why they are an absolute must for home defense.

Its relative scarcity aside, the 458 SOCOM is an all-around excellent cartridge and unparalleled when it comes to slaying feral pigs in rapid succession.

Continue reading more about Best AR Calibers & Cartridges in 2025 here.