300 Blackout vs 338 ARC: The Modern AR Cartridge Showdown

November 28, 2025

As the AR platform continues to evolve, so do the cartridges designed for it. Two of the most talked-about calibers in recent years are the 300 Blackout (300 BLK) and the 338 ARC (Advanced Rifle Cartridge).

Both bring unique strengths to the table...one excelling in suppressed and close-range use, the other pushing the AR’s range and energy to new levels. After extensive range time and ballistic testing, I’ve come to appreciate both for what they offer. Let’s break down how they truly compare.

The Basics

Feature	300 Blackout (300 BLK)	338 ARC
Parent Case	.223 Remington	6.5 Grendel
Bullet Diameter	.308 in (7.82 mm)	.338 in (8.6 mm)
Standard Barrel Twist	1:7 or 1:8	1:8 or 1:9
Effective Range	300–400 yards	800–1000+ yards
Typical Bullet Weight	110–220 grains	175–300 grains
Designed For	Suppressed, short barrels, CQB	Long-range precision, hunting
Platform	AR-15	AR-15 or AR-10 (with modifications)

Field Impressions

Shooting both back-to-back, the differences are instantly noticeable. The 300 Blackout shines in compact AR builds, delivering reliable subsonic performance that pairs perfectly with a suppressor. Recoil is mild, making it ideal for tactical and home defense setups.

The 338 ARC, however, feels like a completely different beast. It offers a flatter trajectory and far greater downrange energy. In a mid-length or full-size AR setup, it can deliver supersonic performance that rivals .308 Winchester, all while staying in a lighter, more compact package.

Ballistic Comparison Chart

Load Type	Velocity (fps)	Energy (ft-lbs)	Drop @ 500 yds (MOA)	Supersonic Range
300 BLK 125 gr (supersonic)	~2,200	~1,340	-70	~500 yds
300 BLK 220 gr (subsonic)	~1,050	~540	-150	~200 yds
338 ARC 200 gr (supersonic)	~2,600	~3,000	-45	~1,000 yds
338 ARC 250 gr (subsonic)	~1,050	~610	-120	~300 yds

Ballistics from 16” test barrels. Results vary with load, barrel length, and conditions.

Sound Suppression Chart

Cartridge	Load Type	Avg. Suppressed dB	Sound Level Comparison
300 BLK (220 gr subsonic)	Subsonic	~125 dB	Nail gun
300 BLK (125 gr supersonic)	Supersonic	~140 dB	Chainsaw
338 ARC (250 gr subsonic)	Subsonic	~128 dB	Slightly louder than 300 BLK
338 ARC (200 gr supersonic)	Supersonic	~142 dB	Chainsaw-level

The 300 Blackout clearly dominates in suppressed shooting, while the 338 ARC trades a bit more noise for significantly more power and range.

Pros and Cons

Feature	300 Blackout	338 ARC
Pros	- Excellent for suppressed fire - Uses standard AR-15 mags - Low recoil - Great in short barrels	- Superior long-range ballistics - High energy for hunting - Impressive accuracy - Maintains velocity beyond 800 yards
Cons	- Limited range - Drops quickly beyond 300 yards - Not ideal for large game	- More expensive ammo - Requires stronger bolt and magazines - More recoil and muzzle blast

Which One Should You Choose?

If your goal is quiet, close-range precision especially for home defense or suppressed tactical use, the 300 Blackout is hard to beat. It’s efficient, reliable, and widely available.

However, if you want to stretch your AR’s capabilities into true long-range hunting or precision shooting, the 338 ARC offers unmatched ballistic performance in a compact package. It’s a powerful bridge between AR-15 practicality and AR-10 power.

Final Thoughts

Both the 300 Blackout and 338 ARC bring modern innovation to the AR world, but they cater to different missions. The 300 BLK excels in silence and agility, while the 338 ARC dominates in reach and power.

If possible, I’d say own both, each one represents a different side of what makes the AR platform so adaptable and capable.

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