Barnes Suppressor Optimized 300 AAC Blackout 220 Grain Sierra MatchKing OTM (MPN: 32518)
When running short-barrel platforms and suppressors in 300 AAC Blackout, the biggest challenge isn't just staying quiet—it's maintaining reliable cycling without choking the action on unburnt powder or destabilizing heavy projectiles. Barnes designed their Suppressor Series specifically to solve the headaches associated with suppressed subsonic setups. Built around the proven 220-grain Sierra MatchKing Open Tip Match (OTM) bullet, this load provides serious shooters, target marksmen, and tactical enthusiasts with exceptionally quiet, movie-silent performance without sacrificing bullet stability or action drive in short gas systems.
The core of this load’s engineering lies in its burn dynamics and projectile seating. Barnes utilizes specialized, fast-burning propellants specifically formulated for suppressed short barrels (typically 7 to 10.5 inches). This ensures complete powder burn inside the tube, drastically reducing port pop, blowback debris, and carbon fouling in your suppressor core. Combined with factory-new, precision-drawn brass cases and premium boxer primers, the heavy 220gr Sierra MatchKing features a boat-tail profile and thin jacket tolerances that maintain rotational balance even out of tight 1:7 or 1:5 twist barrels.
In real-world range testing, expect dead-consistent subsonic velocities around 1,020 FPS out of a standard 16-inch barrel and approximately 980–1,000 FPS out of shorter SBR setups. Felt recoil is exceptionally soft—comparable to shooting a standard rimfire or soft pistol round—allowing for rapid follow-up shots and effortless target retention. Cycling is clean and smooth through both pistol-length gas systems and standard AR-15 magazines, making it one of the most reliable out-of-the-box subsonic factory rounds on the market today.
Armorer Bench Notes & Technical Maintenance Guidance
Shipping Restrictions: Ammunition sales are strictly regulated. Check all state and local laws prior to ordering. Cannot ship to PO Boxes, APO/FPO addresses, or internationally. Must ship via Ground transport.
Armorer Tip: While 220gr subsonic ammo is engineered for quiet shooting, short-barreled rifles (SBRs) under 9 inches may require an adjustable gas block or lighter buffer (such as a standard C-buffer or H1) when unsuppressed to ensure full bolt lockback on the last round. Always check for keyholing at 25 yards on fresh paper before threading your suppressor on to prevent baffle strikes, especially with newly installed fast-twist barrels.
Key Features
- Suppressor-Optimized Propellant: Clean-burning powder formulated to minimize blowback, port noise, and internal suppressor fouling.
- Match-Grade Accuracy: Loaded with legendary 220-grain Sierra MatchKing Open Tip Match (OTM) projectiles.
- Subsonic Velocity: Runs consistently below the speed of sound (~1,020 FPS) to eliminate supersonic crack downrange.
- AR-15 Magazine Compatible: Seated to standard overall length (OAL) for smooth feed-ramp transition in PMAGs and metal mags.
- Reloadable Brass: Premium, new-manufacture boxer-primed brass cases built to strict dimensional tolerances.
Product Specifications
- Brand: Barnes Bullets
- Product Line: Suppressor Series / Precision Match
- MPN: 32518
- UPC: 716876220038
- Caliber / Gauge: 300 AAC Blackout (300 BLK)
- Bullet Weight: 220 Grain
- Bullet Type: Sierra MatchKing Open Tip Match (OTM / HPBT)
- Muzzle Velocity: ~1,020 FPS (Test Barrel dependent)
- Muzzle Energy: ~507 ft-lbs
- Casing Material: Brass (Reloadable)
- Primer Type: Boxer (Non-Corrosive)
- Box Quantity: 20 Rounds per Box
- Case Quantity: 200 Rounds (10 Boxes)
