The .338 ARC (Advanced Rifle Cartridge) is Hornady's big-bore, subsonic-optimized cartridge designed to run in standard AR-15 platforms. The 307-grain SUB-X subsonic load leaves a 16-inch barrel at 1,050 fps with 752 ft-lbs of muzzle energy, hitting roughly 1.5x the energy of equivalent .300 Blackout subsonic. The 175-grain HP Match BLACK supersonic load reaches 2,075 fps from the same barrel with 1,115 ft-lbs at 200 yards. It uses a 6.5 Grendel bolt face, runs in AR-15 magazines, and pairs with .338-cal, .45-cal, or .300 BLK-rated 9mm suppressors. Hornady designed it primarily for hunters and shooters who want big-bore terminal performance from a compact AR-15 platform.
.338 ARC Quick Specs
|
Bullet Diameter |
.338 inches |
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Case capacity / parent case |
Optimized for subsonic; based on 6.5 Grendel/ARC case head |
|
Bolt face |
6.5 Grendel/ARC (.441") |
|
Platforms |
AR-15 and bolt-action |
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Magazine |
338 ARC/400 Legend/6.5 Grendel AR-15 magazines |
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Subsonic Load (Hornady) |
307 gr SUB-X • 1,050 fps from 16" barrel • 752 ft-lbs |
|
Supersonic Load (Hornady) |
175 gr HP Match BLACK • 2,075 fps from 16" barrel • 1,115 ft-lbs at 200 yards |
|
Effective Range (subsonic) |
~200 yards on deer, hog, and similra game |
|
Operating Pressure |
~30,000 PSI subsonic, ~52,000 PSI supersonic |
| Year Introduced | 2023 (Hornady) |
Table of Contents:
What is the .338 ARC?
The .338 ARC (Advanced Rifle Cartridge) is Hornady's newest big-bore cartridge in the ARC family, joining the supersonic-focused 6mm ARC and 22 ARC. Where its siblings target accuracy and reach, the .338 ARC is built around subsonic performance. The case is optimized for the small powder charges subsonic loads require, and Hornady developed a dedicated 307-grain SUB-X bullet for the round.
The result is a big-bore subsonic cartridge that fits in a standard AR-15 platform, it uses commonly available magazines, and runs reliably with both supersonic and subsonic loads from the same upper. That platform compatibility is the whole point: shooters who already own an AR-15 can drop in a .338 ARC upper and get .338-class terminal performance without moving to an AR-10.
Why .338 ARC?
Three things make the .338 ARC interesting:
• Big-bore terminal performance in a small-frame AR platform — no AR-10 required.
• Subsonic-first design — case geometry and powder charges tuned for consistent low-velocity loads, where most subsonic ammo struggles.
• Dual-purpose loads — supersonic 175gr for 200-yard work, subsonic 307gr for suppressed shooting and short-range hunting.
Hornady engineers tailored the case head and shoulder geometry around the small powder volumes subsonic loads use. Most subsonic rifle ammo fills only 25% of the case, which causes inconsistent ignition and large velocity standard deviations. The .338 ARC's case is smaller and uses a shoulder angle optimized for subsonic powders, which produces tighter velocity SDs and tighter groups downrange.
338 ARC Ballistics – Subsonic and Supersonic
Subsonic – 307 gr SUB-X (Hornady)
• Muzzle velocity: 1,050 fps (16" barrel)
• Muzzle energy: 752 ft-lbs
• G1 BC: .375
• Sectional density: .384
• Energy advantage over .300 BLK subsonic: roughly 1.5x
• Bullet construction: SUB-X with Flex Tip insert — designed to expand at velocities as low as 900 fps
Supersonic – 175 gr HP Match BLACK (Hornady)
• Muzzle velocity: 2,075 fps (16" barrel)
• Energy at 200 yards: 1,115 ft-lbs
• Energy at 300 yards: 903 ft-lbs
• Bullet drop at 500 yards: ~118 inches
• Practical effective range (supersonic): treat as a 200-yard cartridge
Barrel-length sensitivity for the supersonic load runs roughly 25-30 fps per inch in either direction. Going shorter than 16 inches gives up some velocity but the round doesn't fall off a cliff — Hornady designed the case to extract reasonable performance from shorter SBR-length barrels.
.338 ARC vs. .300 Blackout
The .300 Blackout has been the dominant AR-15 subsonic cartridge for over a decade. The .338 ARC is the first credible challenger to that position. Here's how they stack up:
• .338 ARC subsonic delivers roughly 1.5x the muzzle energy of .300 BLK subsonic (752 ft-lbs vs ~500 ft-lbs).
• .338 ARC uses a .338-diameter bullet vs .300 BLK's .308-diameter — bigger frontal area, more terminal damage.
• .300 BLK has 10+ years of ammo variety, reloading component availability, and price competition. Expect .300 BLK to stay cheaper for years.
• .300 BLK is the better short-range close-quarters choice for SBRs and indoor work.
• .338 ARC pulls ahead at the edge of subsonic effective range and on game requiring more terminal energy.
If you already own .300 BLK and shoot mostly inside 100 yards, you don't need to switch. If you want maximum subsonic energy for hunting or precision suppressed work out to 200 yards, the .338 ARC is the upgrade.
.338 ARC vs. 8.6 Blackout
Both use .338-diameter bullets and both offer subsonic and supersonic options, but they live on different platforms. The 8.6 BLK runs in AR-10 and short-action bolt rifles — it was designed as the AR-10 successor to .300 BLK. The .338 ARC runs in AR-15 platforms. That's the deciding factor for most shooters:
• Pick 8.6 BLK if you're committed to the AR-10 platform and want maximum supersonic velocity and bullet weight range (160-350gr).
• Pick .338 ARC if you want big-bore performance from your existing AR-15 — lighter, smaller, more compact package.
• Both will share suppressors (.338-cal cans rated for either pressure spec).
There's no clear winner between the two — they're different tools for different platforms. The 8.6 BLK has a larger case and reaches higher supersonic velocities. The .338 ARC sacrifices some of that velocity for AR-15 compatibility and tighter subsonic consistency.
.338 ARC vs. .338 Lapua Magnum
These two cartridges share a bullet diameter and almost nothing else. The .338 Lapua Magnum is a long-action, bolt-gun cartridge designed for extreme long-range shooting — 1,000+ yards with 250-300gr projectiles at velocities above 2,800 fps. The .338 ARC is a short-action AR-15 cartridge designed primarily for subsonic shooting inside 200 yards. They're not interchangeable, they're not competitors, and you wouldn't pick one over the other unless you had no idea what you were doing.
• .338 Lapua: 1,000+ yard precision, bolt-action, full-power magnum, heavy bullets, expensive ammo (~$5-8/round).
• .338 ARC: 200-yard subsonic/supersonic in an AR-15, far cheaper ammo, far more compact platform, far less recoil.
If you need to make 1,200-yard hits on steel, you want a .338 Lapua. If you want a quiet big-bore AR-15 for hunting or suppressed shooting, you want the .338 ARC.
Hunting with .338 ARC
Hornady's engineers said subsonic hunting was at the forefront of .338 ARC development, and they've reportedly done extensive game-testing with the cartridge. Their stated effective range for the subsonic load is roughly 200 yards on deer, hog, and similar-sized game.
What makes the .338 ARC a good hunting cartridge:
• AR-15 compatibility means lighter rifles and SBR-friendly hosts.
• Heavy 307gr subsonic bullets generate substantially more terminal energy than .300 BLK subsonic.
• Subsonic + suppressor combination is genuinely quiet — useful for property work, public lands where noise matters, or hunting with neighbors close by.
• Supersonic loads extend effective range without changing the upper.
• Tight subsonic group consistency (smaller velocity SDs from the optimized case design).
Where it falls short: anything past 200 yards on game. The cartridge is purpose-built for short-to-medium-range work. For longer shots, supersonic loads still get you there — but the .338 ARC isn't a substitute for a real long-range cartridge.
Suppressors for 338 ARC
A suppressor transforms the .338 ARC, especially the subsonic load. The combination is one of the quietest big-bore platforms commercially available, and Hornady specifically designed the round with suppressor use in mind. The .338 ARC's operating pressures (~30,000 PSI subsonic, ~52,000 PSI supersonic) are compatible with any suppressor rated for .300 BLK or 8.6 BLK — verify with your specific can’s manufacturer if you're unsure.
.45 Caliber Suppressors for .338 ARC
Large-bore .45-cal silencers handle the .338 ARC easily. If you already own one as a universal pistol can, you're set — they cover everything from .45 ACP to .338-class rifle calibers. Strong .45-cal picks for .338 ARC use:
9mm Suppressors for .338 ARC
Some 9mm suppressors rated for higher pressures (.300 BLK or 8.6 BLK pressure spec) will run the .338 ARC because the bore diameters (.355 vs .338) are close enough. Verify with your suppressor manufacturer before running it. When compatible, this gives you a smaller, lighter package.
.338 -Caliber Suppressors for .338 ARC
Dedicated .338-cal suppressors are the optimized choice. Quieter than the .45-cal cans (smaller bore, better gas containment), lighter than full magnum cans, and purpose-built for the bullet diameter. Strong picks:
.338 ARC Parts Compatibility
The .338 ARC was designed to drop into existing AR-15 platforms with minimal new parts:
• Bolt: 6.5 Grendel bolt (same .441" bolt face).
• Magazines: Standard 6.5 Grendel-compatible AR-15 magazines (e.g., Lancer L5, ASC).
• Lower receiver: Standard AR-15 lower — no modifications needed.
• Buffer / spring: Standard AR-15 buffer system, though some shooters report better cycling with an H2 or H3 buffer for the supersonic load.
• Barrel and gas system: Dedicated .338 ARC barrel required; available in 8.5", 10.5", 12.5", 16", and 20" lengths from multiple manufacturers.
If you already have an AR-15 lower, getting into .338 ARC means adding an upper assembly and a few magazines. Easier on the budget than committing to a new platform like the AR-10 for 8.6 BLK.
Frequently Asked Questions
What is the .338 ARC effective range?
Treat the .338 ARC subsonic load as a 200-yard cartridge on deer, hog, and similar-sized game. The supersonic 175gr load extends to about 300+ yards before energy drops below comfortable ethical-hunting levels. The cartridge is not a long-range round — it's purpose-built for short-to-medium-range work.
Will my .338 ARC work in an AR-15?
Yes. The .338 ARC was specifically designed to run in standard AR-15 lower receivers. You need a dedicated .338 ARC upper assembly, 6.5 Grendel-compatible magazines, and a 6.5 Grendel bolt. Everything else is standard AR-15.
Is the .338 ARC better than .300 Blackout?
It depends on your use case. The .338 ARC delivers roughly 1.5x the subsonic energy of .300 BLK and is the better choice for hunting or maximum subsonic terminal performance. The .300 BLK is still better for very close-range work, has cheaper and more varied ammo, and a deeper bench of host options. Both are excellent — pick based on what you're shooting at and how far.
Can I shoot .338 ARC with my .300 BLK suppressor?
If your suppressor's bore is .338 or larger, yes. If your suppressor is bore-rated for .300 BLK (.308 caliber), no — the .338 bullet won't fit. Check your suppressor's bore diameter before running .338 ARC through it. Large-bore .45-cal cans, .338-cal cans, and some 9mm cans rated for higher pressures all work.
What magazines does the .338 ARC use?
Standard 6.5 Grendel-compatible AR-15 magazines, 400 Legend magazines, and new magazines optimized for 338 ARC specifically. Lancer L5, ASC, and most 6.5 Grendel-marked AR-15 mags will feed .338 ARC reliably, we have had excellent results from DuraMags.
Is the .338 ARC a real cartridge or just hype?
Real cartridge. Hornady introduced it in 2023, ammunition is in commercial production (Hornady 307gr SUB-X subsonic and 175gr HP Match BLACK supersonic), and multiple rifle manufacturers including PSA, CMMG, Sig Sauer, and Wilson Combat are offering uppers or complete rifles in the chambering. The platform support is there.
What suppressor is best for .338 ARC?
For dedicated .338 ARC use, a .338-cal suppressor like the Dead Air Nomax 33, Rugged Alaskan 360, FOR Systems Predator 8.6, or SilencerCo Omega 36M is the optimized choice. If you want a more versatile can, a large-bore .45-cal like the SilencerCo Hybrid 46M will handle everything from .45 ACP to .338 ARC. The decision comes down to whether you want optimization for this specific cartridge or maximum versatility across multiple hosts.
Is .338 ARC good for hunting?
Yes, especially suppressed subsonic hunting on deer, hog, and similar-sized game inside 200 yards. The 307gr subsonic SUB-X bullet was designed specifically for terminal performance at subsonic velocities. Outside 200 yards, you're better off in supersonic loads or with a different cartridge entirely.
How does .338 ARC compare to .338 Lapua Magnum?
They share only the bullet diameter. The .338 Lapua is a long-action magnum cartridge for 1,000+ yard precision shooting from bolt rifles. The .338 ARC is a short-action AR-15 cartridge for 200-yard subsonic and supersonic shooting. Different platforms, different ranges, different ammo costs, different use cases. They are not substitutes for each other.
Where can I buy a .338 ARC rifle?
Multiple manufacturers offer .338 ARC uppers and complete rifles, including CMMG, Sig Sauer, and Wilson Combat. Ammunition is widely available from Hornady. For suppressors compatible with .338 ARC, Silencer Shop carries every major option in .338-cal, .45-cal, and higher-pressure 9mm configurations.
