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The .338 ARC has quickly become one of the most talked about new cartridges in the suppressed shooting world. Designed specifically for close range suppressed use, the cartridge promises significantly more energy than 300 Blackout while still maintaining compatibility with the AR15 platform. Recently, we got the opportunity to spend time testing PSA’s new .338 ARC upper to see how the platform performs in the real world.
One of the biggest advantages of PSA’s setup is the lower cost of entry. Instead of requiring a completely new rifle platform, the .338 ARC works on a standard AR15 lower, and PSA’s upper comes in at around the $400 price range. That makes it far more approachable than many other niche suppressed rifle setups.
Over the course of testing, we put roughly 500 rounds through the upper using both supersonic and subsonic ammunition while running the rifle primarily suppressed.
What Is the .338 ARC?
The .338 ARC was introduced near the end of 2025 and was designed around heavy subsonic projectiles and suppressed shooting. The cartridge is based off the 6 ARC and 6.5 Grendel family of cartridges but shortened and necked up to accept .338 caliber projectiles.
Compared to 300 Blackout, the .338 ARC delivers roughly 50 percent more energy on target at 100 yards while still functioning inside the AR15 platform.
That makes it especially appealing for shooters looking for stronger subsonic performance without moving to a larger AR10 platform like they would with 8.6 Blackout.
PSA .338 ARC Upper Breakdown
PSA’s upper uses an 8.5 inch barrel made from 4150 chrome moly vanadium steel with a medium profile and 5/8x24 thread pitch. The upper ships with a standard A2 flash hider, though we tested ours using a Dead Air Xemax Brake to pair with the Dead Air Nomax 33.
One important thing to note is suppressor compatibility. Even though the barrel uses the common thread pattern, .338 projectiles are larger than standard .30 caliber suppressor bores. Because of that, larger bore suppressors such as 9mm or .45 caliber suppressors are required.
The upper also features an adjustable pistol length gas system paired with a 7 inch MLOK handguard and full length Picatinny rail. During testing, the gas system handled both subsonic and supersonic ammunition reliably without requiring much adjustment.
The upper uses a forged 7075 T6 receiver along with a full auto profile bolt carrier group featuring a shot peened 9310 steel bolt and 8620 carrier.
PSA currently ships the upper with a 400 Legend magazine. Because magazine compatibility for .338 ARC is still evolving. Standard 6.5 Grendel magazines have produced mixed results due to the cartridge geometry and larger projectile diameter.
Reliability and Accuracy
Overall reliability during testing was solid. Across approximately 500 rounds, we experienced only two failures to feed, both involving the first round from fully loaded magazines hanging on the feed ramp after releasing the bolt. Once the rifle was cycling, we experienced no failures to eject or additional feeding problems.
Accuracy was also impressive for such a compact suppressed focused setup. Using AAC 175 grain OTM ammunition, the rifle consistently grouped around 1 MOA. With AAC 300 grain subsonic hollow points, groups opened closer to 2 MOA, which is still perfectly acceptable for the cartridge’s intended role.
The Downsides
The biggest downside to the .338 ARC right now is ammunition availability and cost. AAC originally launched .338 ARC loads alongside PSA’s release, but powder shortages and supply chain issues have made ammunition difficult to find consistently.
Subsonic .338 ARC ammunition currently costs substantially more than 300 Blackout, though it still remains cheaper than most 8.6 Blackout loads.
Magazine capacity is another limitation. Current magazine options are limited to around 10 rounds with this upper from PSA, which may be a drawback for some shooters.
Final Thoughts
The .338 ARC fills a very interesting role in the modern AR15 market. It offers substantially more energy than 300 Blackout while maintaining the compact size and lighter weight of the AR15 platform. Combined with PSA’s relatively affordable upper pricing, it creates a much lower barrier to entry for shooters interested in a dedicated suppressed setup.
The platform still has room to mature, especially regarding magazines and ammunition availability, but after spending time with the upper, the .338 ARC already feels like one of the most promising new suppressed AR15 cartridges currently available.
