Atomic 300 Blackout 220gr Subsonic HPBT Ammo – Reliable 20 Round Box

Description

The Atomic 300 Blackout 220gr Subsonic is a 20 round box of 300 AAC Blackout rifle ammunition built for one job: quiet shooting through a suppressor without giving up semi-automatic function. Atomic Ammunition is an American company that hand-loads its cartridges in small batches, and this 220 grain load is the one most 300 BLK owners reach for when they put a can on the rifle.

Atomic 300 Blackout 220gr Subsonic Overview

Subsonic ammunition stays below roughly 1,125 feet per second, so the bullet never creates the sharp supersonic crack that a suppressor cannot remove. Atomic lists this load at about 1,050 fps from a typical test barrel. The heavy 220 grain projectile carries more momentum at that speed than lighter bullets would, which helps it run the gas system and hit with authority at short to moderate range. Because each round is assembled and inspected in smaller lots, Atomic aims for consistent powder charges and seating depth from box to box.

That consistency matters with subsonic loads, where small velocity swings can mean the difference between a rifle that cycles and one that short-strokes.

Built to Cycle Quietly

Many subsonic loads are quiet but leave the shooter working the charging handle after every shot. Atomic designs this cartridge to produce enough gas pressure to cycle a properly set up suppressed AR-15 while staying subsonic. Results still depend on your rifle. Barrel length, gas port size, gas system length, buffer weight and whether a suppressor is attached all change how much energy reaches the bolt carrier. Pistol-length gas systems on short barrels usually cycle subsonic ammo most easily. If your rifle short-strokes, an adjustable gas block or a lighter buffer often fixes it.

Test a full box before you trust any subsonic load for serious use.

Bullet Construction

Each cartridge uses a 220 grain bullet with a hollow point boat tail design. The boat tail improves the ballistic coefficient so the bullet holds velocity a little better downrange, and the hollow point nose is typical of match-style projectiles. At subsonic speed, do not expect dramatic expansion from any hollow point; the heavy bullet relies more on mass and penetration than on rapid mushrooming.

That makes it a sensible choice for target work, pest control at close range and practice with a suppressor, but hunters should research performance on game and check local regulations before taking it into the field.

Ballistics and Trajectory

Atomic rates the load at about 538 ft-lbs of muzzle energy. That is far less than supersonic 300 BLK loads in the 110 to 125 grain class, and the trajectory is noticeably more curved. Past 100 yards the bullet drops quickly, so learn your holdovers on paper before stretching distance. Many owners zero their optic for supersonic ammo and simply memorize the point-of-impact shift for subsonic rounds; others run a dedicated subsonic zero. Whichever approach you choose, confirm it at the range rather than relying on a ballistic app alone.

Suppressor Notes

A suppressor is an NFA item. Buying one requires an approved ATF Form 4, and some states do not allow civilian ownership at all, so confirm that your state permits it before you build around subsonic ammunition. Heavy subsonic loads also put more carbon and unburned powder back into the action than supersonic ammunition, especially with a can attached. Plan on cleaning the bolt carrier group and chamber more often, and keep the rifle lubricated so it continues to cycle reliably.

Rifle Compatibility

This ammunition is for firearms chambered in 300 AAC Blackout, also marked 300 BLK or 300 BO. Never load it into a 5.56 NATO or 223 Remington rifle. The two cartridges fit the same magazines and can look similar at a glance, and a 300 BLK round can chamber in a 5.56 barrel and cause a catastrophic failure. Mark your magazines clearly and keep the ammunition separated if you own both calibers.

Caliber Mix-Up Warning

It is worth saying twice: keep this 300 BLK load away from your 5.56 rifles and magazines. Colored magazine baseplates, paint pen marks on the cases of your mags, or simply storing the two calibers in different ammo cans all help prevent a mix-up at the range.

A Note on Listings

One distributor catalog lists this UPC under a 308 Winchester description, while the manufacturer and other distributors identify it as 300 AAC Blackout. Check the headstamp when your box arrives, and contact us if anything does not match.

Specifications

• Brand: Atomic Ammunition
• Caliber: 300 AAC Blackout (300 BLK)
• Bullet weight: 220 grain
• Bullet type: HPBT match-style projectile
• Muzzle velocity: about 1,050 fps (manufacturer rating)
• Case: brass, boxer primed
• Count: 20 rounds per box
• UPC: 860012884308
• Made in the USA

Before You Buy

Federal law requires buyers of rifle ammunition to be at least 18 years old from a licensed dealer. Some states and cities restrict ammunition purchases, require background checks or limit shipping, so check your local rules before you order.

Who It Is For

The Atomic 300 Blackout 220gr Subsonic is a great fit for owners of suppressed 300 BLK rifles and pistols who want a quiet load that still runs the gas system, and for shooters who simply enjoy low-recoil, low-noise practice.

Buy the Atomic 300 Blackout 220gr Subsonic at MAG5 Firearms

MAG5 Firearms is a family-owned FFL in Collegeville, Pennsylvania. Order the Atomic 300 Blackout 220gr Subsonic online and we will ship it to you where state and local law allow, or browse our full selection of ammunition for more rifle loads. For factory details, visit Atomic Ammunition.