Description
The SIG Sauer 300 BLK 220gr Match Subsonic is a precision subsonic load built around a 220 grain Sierra MatchKing open tip match bullet. SIG rates it at roughly 1,000 fps with about 488 ft-lbs of energy, keeping it below the speed of sound so it runs quietly through a suppressor. It is loaded in nickel-plated cases, packed 20 rounds per box, and made in the USA.
What You Get With the SIG Sauer 300 BLK 220gr Match Subsonic
The heart of this cartridge is the Sierra MatchKing, one of the most widely used match bullets in precision shooting. Its boat tail and open tip design are aimed at consistent flight and tight groups rather than expansion. SIG says each round is precision loaded using electro-mechanical monitoring to check geometric conformity, which is intended to keep round-to-round variation low.
Subsonic loads exist to pair with suppressors. Supersonic bullets create a sonic crack that no suppressor can remove, so staying below roughly 1,100 fps lets a can do its job. This makes the SIG Sauer 300 BLK 220gr Match Subsonic a natural fit as suppressed rifle ammo for 300 Blackout AR builds, SIG MCX rifles, and bolt guns chambered in 300 BLK.
The cases are nickel plated, boxer primed and reloadable. Nickel plating resists corrosion and tends to feed smoothly, and handloaders can keep the brass for later use.
Practical Notes Before You Buy
Cycling is the most common question with any 300 Blackout subsonic ammo. Heavy subsonic loads produce less gas than supersonic ammunition, and some gas-operated rifles, particularly those with rifle-length gas systems or heavy buffers, may short-stroke when run unsuppressed. Most carbines and pistols set up for 300 BLK run reliably with a suppressor attached, and an adjustable gas block helps. Test the SIG Sauer 300 BLK 220gr Match Subsonic in your rifle before relying on it.
Barrel twist also matters. Long, heavy 220 grain bullets need a fast twist to stabilize at low velocity. Most 300 BLK barrels use a 1:7 or 1:8 twist, which is appropriate. Slower twists may produce keyholing.
Because this is a match bullet, it is designed for accuracy rather than reliable expansion at subsonic speed. For hunting, a subsonic bullet engineered to expand at low velocity is usually a better choice. Most importantly, never chamber 300 BLK ammunition in a 5.56 or 223 rifle. The cartridges can physically fit and firing one can destroy the rifle and injure the shooter. Label magazines clearly if you own both calibers.
SIG Sauer 300 BLK 220gr Match Subsonic Specifications
- Brand: SIG Sauer
- Line: Marksman Match
- Part Number: C300A2-20
- Caliber: 300 AAC Blackout
- Bullet: 220 grain Sierra MatchKing open tip match (OTM)
- Velocity: approx. 1,000 fps (manufacturer rating)
- Energy: approx. 488 ft-lbs
- Case: nickel-plated brass, boxer primed, reloadable
- Rounds per Box: 20
- Country of Origin: USA
- UPC: 798681726622
Why Shooters Choose the SIG Sauer 300 BLK 220gr Match Subsonic
Many suppressed shooters look for consistency above all else, and the SIG Sauer 300 BLK 220gr Match Subsonic delivers a known match bullet in a quality case at a reasonable price for premium subsonic ammunition. It is a solid choice for suppressed plinking, precision practice at moderate range, and zeroing a subsonic setup.
Keep expectations realistic about range. A 220 grain OTM bullet at subsonic speed drops sharply past 100 to 150 yards, so dial or holdover data matters. Suppressor ownership also requires an approved ATF Form 4, a $200 tax stamp where applicable, and compliance with state law, since some states prohibit suppressors entirely.
Browse the MAG5 Firearms ammunition selection for more 300 Blackout loads, and see SIG Sauer for full ammunition details.
Who it is for: 300 Blackout owners running a suppressor who want accurate, consistent subsonic ammunition with a 220 grain OTM match bullet. Store ammunition in a cool, dry place away from children and follow all federal, state and local laws when purchasing and transporting the SIG Sauer 300 BLK 220gr Match Subsonic.
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