AR-15 Ammo Selection Guide: Everything You Need to Know

The AR-15 rifle platform offers unmatched modularity, reliability, and accuracy. With the ability to change calibers, barrels, stocks, optics, and more, the AR-15 can be customized for various applications from target shooting to home defense. However, one of the most important components that can significantly impact performance is the ammunition.

Choosing the right ammo for your AR-15 build is crucial to achieving the best accuracy, power, and reliability. This comprehensive guide will walk you through the key factors to consider when selecting AR-15 ammunition so you can find the optimal rounds for your needs.


The AR-15 rifle utilizes a wide variety of ammunition from small varmint rounds like the .223 Remington to larger hunting cartridges like the 6.5 Creedmoor. With the rifle’s popularity and modular design, manufacturers have developed loads in various calibers and bullet weights to meet any application.

However, with so many options available, it can be challenging to select the ideal ammo for your particular AR-15 setup. This guide will provide an overview of the critical considerations when choosing AR-15 ammo so you can confidently pick the loads that will provide the best performance for your intended use.

Types of AR-15 Ammo

While there are many calibers and loads available for the AR-15, most ammunition falls into a few common categories:

.223 Remington/5.56x45mm NATO

The .223 Remington and nearly identical 5.56x45mm NATO are the most popular AR-15 chamberings. The .223 Rem offers a lightweight, flat-shooting round effective for target shooting, small game hunting, and varmint control. The 5.56 NATO provides higher pressures for increased velocity and performance. Both are available in a wide variety of bullet weights optimized for various applications.

6.5 Grendel

The 6.5 Grendel provides significantly improved ballistics over the .223 Remington for longer range shooting. Its flatter trajectory and wind-bucking abilities make it an excellent cartridge for precision shooting out to 800+ yards. The moderate recoil also makes it a versatile hunting round.

6.8 SPC

Designed to increase terminal performance over the M855 5.56 NATO round, the 6.8 SPC has gained a strong following in tactical circles. It provides stopping power between the 5.56 NATO and 7.62 NATO with minimal loss of magazine capacity. The soft recoil makes it popular for competition use as well.

300 Blackout

The 300 BLK was created to match 7.62x39mm ballistics in a standard AR-15 while using existing 30 caliber bullets. Subsonic loads excel in suppressed AR platforms. The supersonic loads offer increased power over the 5.56 NATO round as well.


With similar ballistics to the AK-47 round, using 7.62x39mm ammo in an AR-15 allows you to utilize inexpensive steel-cased ammunition with enhanced AR accuracy and reliability. Both supersonic and subsonic loads are available.

Common AR-15 Calibers

While the AR-15 is available in a wide variety of calibers from .22 LR up to .50 Beowulf, most rifles will be chambered for one of these common calibers:

.223 Remington – The .223 Rem is the standard AR-15 caliber, providing a versatile lightweight round suitable for target shooting, small game hunting, and home defense. It is also compatible with the similar 5.56 NATO round.

5.56 NATO – The 5.56x45mm NATO offers higher pressures than the .223 Remington, resulting in increased muzzle velocity. This provides better performance at extended ranges. It can be safely used in .223 Rem chambers.

300 Blackout – Designed to match 7.62x39mm ballistics, the 300 BLK excels with subsonic ammo in suppressed AR-15s. It also provides more power than the 5.56 NATO in a standard AR magazine.

6.5 Grendel – The 6.5 Grendel offers superior ballistics to the .223 Rem, with a flatter trajectory, less wind drift, and more energy on target. It excels in precision, long-range shooting applications.

6.8 SPC – With minimal loss in magazine capacity, the 6.8 SPC improves terminal performance over the 5.56 NATO. Its moderate recoil also makes it popular for competition use.

7.62x39mm – The 7.62x39mm allows you to utilize inexpensive steel-cased Russian ammo in an AR-15 for reduced cost training. Both supersonic and subsonic loads are available.

Key Factors in AR-15 Ammo Selection

Choosing the right ammunition for your AR-15 rifle depends on several important factors:

Intended Use

Think about how you plan to use your AR-15 – target shooting, home defense, hunting, competition, etc. Your intended use will largely determine the best caliber and bullet type to choose.

Maximum Effective Range

Consider the maximum distance you need the ammunition to perform. Long range precision shooters will benefit from rounds like 6.5 Grendel or 6.8 SPC while .223/5.56 NATO is sufficient for typical defensive ranges.


Match grade ammunition provides the greatest accuracy for competitive and precision shooting. For defensive use, adequate accuracy from quality factory ammo is acceptable.


If stopping power is critical for hunting or home defense applications, larger calibers like .300 Blackout or 6.5 Grendel provide more energy on target than lighter .223/5.56 rounds.

Recoil Sensitivity

If you are sensitive to recoil or need fast follow up shots, calibers like .223 Remington or 6.8 SPC will offer less felt recoil than larger cartridges.


Steel-cased 7.62x39mm provides the most affordable high volume shooting option. Match grade loads for maximum accuracy carry a price premium.


Popular rounds like .223/5.56 NATO allow flexibility if ammo shortages occur. Larger specialty calibers may have limited availability during high demand.

By evaluating these key factors, you can narrow down your choice to the ideal AR-15 caliber and ammunition to suit your specific needs.

AR-15 Caliber and Ammo for Key Applications

Here are some of the most common uses for an AR-15 rifle and the preferred calibers and ammunition types for each application:

Target and Plinking

For informal target shooting and plinking, .223/5.56 NATO is perfectly suitable and affordable. Bulk pack 55gr or 62gr FMJ rounds offer accuracy with minimal cost.

Home Defense

For home defense applications, the .223 Remington and 5.56 NATO provide sufficient power in a controllable package. Look for quality hollow point or soft point ammunition from reliable self-defense brands.

Varmint and Predator Hunting

When hunting small game like coyotes or prairie dogs, lighter .223 Rem/5.56 NATO loads with bullets weighing 55gr or less allow rapid follow up shots with devastating terminal effects.

Big Game Hunting

For deer-sized game, the 6.5 Grendel is an excellent choice, providing superior ballistics and energy on target over the .223 Remington. Quality hunting ammunition with controlled expansion is key.

Long Range Precision

For precision shooting at extended distances, the 6.5 Grendel and 6.8 SPC really shine. Look for heavier match grade bullets choosing a load that provides the highest BC, velocity, and accuracy.

Suppressed Use

For optimized performance with a suppressed AR-15, 300 BLK was designed specifically for this application. Subsonic 185gr to 220gr expanding rounds excel.

Competition Shooting

In formal competitive shooting sports, match grade ammunition provides the consistency and precision needed to maximize scores. Look for proven loads from respected manufacturers.

By matching your ammunition selection to your specific shooting application, you will get the ideal performance from your AR-15 rifle.

Ballistics of Common AR-15 Rounds

Understanding the ballistic performance of different AR-15 ammunition is key to selecting the right load for your needs. Here is a comparison of the ballistics for some of the most common AR-15 calibers and loads:

Caliber.223 Remington5.56 NATO6.5 Grendel6.8 SPC.300 Blackout
Bullet Weight55gr62gr123gr115gr125gr
Muzzle Velocity3,240 fps3,100 fps2,575 fps2,725 fps2,215 fps
Muzzle Energy1,282 ft-lbs1,323 ft-lbs1,932 ft-lbs1,691 ft-lbs1,360 ft-lbs
500 Yard Velocityn/a1,758 fps1,651 fps1,628 fps1,006 fps
500 Yard Energyn/a551 ft-lbs907 ft-lbs734 ft-lbs473 ft-lbs
Sectional Density.
Ballistic Coefficient.255.295.435.300.160

As you can see, the 6.5 Grendel and 6.8 SPC maintain velocity and energy downrange much more effectively than lighter 55gr .223 Remington loads. The 6.5 Grendel’s high sectional density and ballistic coefficient provides the flattest trajectory and least wind drift of these common AR-15 rounds.

Best Brands for AR-15 Ammo

While there are plenty of brands producing AR-15 ammunition, a few manufacturers stand out by offering high quality and consistent performance from their loads:

Federal: Well-known ammo giant that offers specialized tactical, target, and hunting loads. Their Gold Medal Match series leads the way.

Hornady: Renowned for match grade accuracy and their precision engineered hunting bullets. Great choice for critical applications.

Winchester: Produces a full range of AR-15 rounds for plinking, target shooting, and hunting. Offers quality at a reasonable price point.

Black Hills: Known for assertion and innovative loadings. Excellent match grade and self-defense ammo options.

Nosler: Premium hunting ammunition loaded with their accurate, high BC match bullets. Provides outstanding performance on game.

Prvi Partizan: Impressive quality for affordable high volume shooting. Loaded in Serbia to tight NATO specs.

While most major ammo companies produce AR-15 loads, these brands have earned strong reputations for providing the utmost in reliability, consistency, and accuracy from their rifle ammunition.

AR-15 Ammo Cost Considerations

Cost is always a factor to weigh when buying ammunition. Cheaper plinking ammo allows for more range time and training. Premium match grade loads provide maximum precision when accuracy is paramount. Here are some tips for balancing performance and budget when selecting AR-15 ammo:

  • Buy in Bulk – Buying larger quantities of ammo saves money compared to box prices. Split bulk orders with friends.
  • Consider Steel-Cased – Affordable steel-cased ammo like Tula and Wolf allow high round count training. Just be aware of increased wear on extractors.
  • Choose Less Premium Brands – Federal, PMC, and Independence make quality rounds for less than premium brands.
  • Compare Prices Online – Shop online to find best deals on ammo from various retailers and take advantage of free shipping offers.
  • Buy Match Loads by the Round – Purchase smaller quantities of expensive match ammo for zeroing and competitions only.
  • Consider Reloading – Reloading saves ~50% per round. Upfront costs are high but reloading pays off after 1,000+ rounds.

With a bit savvy shopping, you can find quality AR-15 ammunition at a reasonable price to suit your budget.

Storing and Maintaining Your AR-15 Ammo

Properly storing and maintaining your ammunition will ensure it stays in optimum condition. Here are some guidelines for taking care of your AR-15 rounds:

  • Avoid Temperature Extremes – Store ammo away from direct sunlight, flames or other heat sources, and extreme humidity.
  • Use a Cool, Dry Place – The ideal storage temperature range is between 55°F and 70°F with low humidity.
  • Keep Away from Solvents – Don’t store ammunition near harsh chemicals like gun cleaning solvents.
  • Use a Sealed Container – Airtight ammo cans or boxes with desiccant packs prevent corrosion issues.
  • Avoid Dropping Rounds – Dents or deformities on a cartridge from drops can cause feeding issues.
  • Inspect Regularly – Periodically check rounds for any signs of corrosion or damage and separate out bad rounds.
  • Clean the Rifle Regularly – A dirty rifle chamber and magazine can damage ammunition and affect reliability.

By properly maintaining both your rifle and ammunition supply, you can ensure flawless functioning and accuracy when your AR-15 hits the range.

Reloading AR-15 Ammo

Reloading spent brass allows you to customize your AR-15 ammunition for enhanced performance at around half the cost of buying factory loads. Here are some pointers for getting started reloading:

  • Choose a Single-Stage or Progressive Press – These provide the best flexibility for high volume reloading.
  • Get Quality Dies – Dies size, deprime, and seat bullets. Go with respected brands like RCBS, Redding, and Hornady.
  • Select the Right Powder – Look for fast-burning powders like H322, BL-C(2), or CFE 223 for .223/5.56 rounds.
  • Consider Specialty Bullets – Choose premium match grade or hunting bullets for your application. Sierra, Nosler, and Berger are top brands.
  • Follow Load Data Carefully – Use reloading manuals to find tested recipes. Work up cautiously to max pressures.
  • Continually Inspect – Check each case, primer, powder charge, seating depth, and overall cartridge as you go.

With handloads, you can build ammo tailored specifically for your AR-15 and shooting purposes while saving money.

AR-15 Ammo Safety

When handling and shooting any ammunition, safety should always be the top concern:

  • Follow All Firearm Safety Rules – Keep your AR-15 pointed in a safe direction at all times when loaded.
  • Use Eye and Ear Protection – Wear ANSI-rated shooting glasses and earmuffs when shooting to prevent injury.
  • Ensure Proper Storage – Keep bulk ammunition sealed in ammo cans away from heat, sparks, and solvents.
  • Avoid Excessive chamber Heat – Allow barrels to cool between magazines to prevent cook-offs or detonation issues.
  • Check for Squib Loads – Stop immediately if reduced recoil indicates an obstructed barrel and clear it.
  • Know Your Target – Ensure you have a proper backstop anytime you fire and know what lies beyond it.

By putting safety first and using common sense when handling ammunition and shooting your AR-15, you can have complete confidence and peace of mind.

Matching AR-15 Ammo to Your Needs

Selecting the right AR-15 ammunition requires understanding your intended use, maximum effective range requirements, desired accuracy, power needs, recoil tolerance, and budget. With a wide range of loads across many calibers now available for the AR platform, you can dial in the optimal ammo for your specific rifle setup and shooting applications.

Taking the time to evaluate the critical factors and test different loads at the range will allow you to extract the best precision and performance possible from your AR-15 rifle. Just remember to always make safety the top priority whenever you are handling and shooting ammo. With the proper ammunition selected for your needs, you will be able to enjoy your AR-15 to its fullest potential.