Out of stock
SKU: A00408
UPC: 858767004089
MPN: 00408
Atomic Ammunition's 5.56x45mm NATO Subsonic load fills a specific role in the rifle ammunition market: quiet, controllable fire from suppressed AR-pattern rifles without sacrificing semi-automatic function. The 112-grain soft point round nose projectile travels at 1050 fps—well below the supersonic threshold—producing approximately 275 ft-lbs of muzzle energy comparable to standard 9mm loads. This makes it a practical choice for shooters running suppressed 5.56 platforms who want reduced noise signature without switching to a different caliber system entirely.
The heavy 112-grain bullet requires a fast twist rate to stabilize properly. Atomic specifies rifles with 1:7-inch twist or faster for reliable accuracy—this rules out many older .223 Remington chambers and slower-twist barrels common on varmint rifles. The brass-cased construction supports reloading, and each round undergoes hand inspection during Atomic's quality control process. Designed specifically for tactical cycling, this ammunition maintains enough back pressure to reliably operate gas-driven semi-automatic actions in compatible rifles. One critical note: this is 5.56x45mm NATO chamber pressure ammunition and should not be fired in rifles chambered only for .223 Remington.
Close-quarters applications under 25 yards represent the sweet spot for this subsonic load. Law enforcement training scenarios, home defense setups with suppressed SBRs, and backyard pest control where noise reduction matters all benefit from the reduced report and minimal recoil. The soft point design provides controlled expansion at subsonic velocities where hollow points may not reliably open. Each box contains 50 rounds, with cases shipping 10 boxes for a total of 500 rounds. For additional 5.56 ammunition options across different use cases, we stock supersonic loads for longer-range work.
| Specification | Detail |
|---|---|
| Brand | Atomic Ammunition |
| Model/MPN | 00408 |
| SKU | A00408 |
| UPC | 858767004089 |
| Shipping Weight | 1 lb |
| Caliber | 5.56x45mm NATO |
| Bullet Weight | 112 grain |
| Bullet Type | Soft Point Round Nose (SPRN) |
| Muzzle Velocity | 1050 fps |
| Muzzle Energy | 275 ft-lbs |
| Casing Material | Brass |
| Rounds Per Box | 50 |
| Boxes Per Case | 10 |
| Barrel Twist Requirement | 1:7" or faster |
| Country of Origin | USA |
This ammunition is designed to cycle semi-automatic actions in most modern AR-15 platforms with proper gas system tuning. Results may vary depending on your specific rifle's gas port size, buffer weight, and suppressor backpressure. Rifles with adjustable gas blocks offer the best tuning flexibility for subsonic loads.
No. Atomic explicitly states this 5.56x45mm NATO ammunition should not be fired in firearms chambered only for .223 Remington. The 5.56 NATO cartridge operates at higher chamber pressures than .223 Remington specifications allow. Use only in rifles chambered for 5.56x45mm NATO or .223 Wylde.
Atomic recommends rifles with 1:7-inch twist or faster for proper bullet stabilization and accuracy. Most modern AR-15 rifles ship with 1:7 or 1:8 twist barrels. Slower twist rates like 1:9 or 1:12 common on older rifles and varmint barrels will not stabilize this heavy projectile.
The subsonic velocity of 1050 fps eliminates the supersonic crack that accounts for much of a rifle's report. Combined with a quality suppressor, this significantly reduces overall noise. However, 'hearing safe' depends on your specific suppressor's decibel reduction—most shooters still recommend ear protection.
Atomic recommends this ammunition for use within 25 yards or meters. The subsonic velocity and resulting rainbow trajectory limit practical accuracy at longer distances. This is close-quarters ammunition designed for suppressed tactical applications, not precision shooting at extended range.
WARNING ⚠️ You must be 18 or older to purchase shotgun or rifle ammunition and 21 or older to purchase handgun ammunition and firearms. Please reference our requirements for ammunition orders to "restricted" states HERE. Always make sure you use the correct ammunition for your firearms. Ammo cannot be shipped to a PO Box. Please reference state & local laws before making a firearm or ammunition purchase.
