How do supersonic and subsonic .300 Blackout differ?
Supersonic and subsonic describe velocity relative to the local speed of sound, not separate cartridge designations. The speed of sound depends on atmospheric conditions.
Supersonic loads exceed the local speed of sound. Verify the exact manufacturer's velocity and test conditions rather than assigning one velocity to a bullet-weight range.
Subsonic loads remain below the local speed of sound under the relevant conditions. The label does not establish cycling, terminal performance, or hearing safety.
Do not infer firearm, magazine, or suppressor compatibility from a shared cartridge category. Follow the equipment and ammunition manufacturers' guidance for the exact load and configuration.
Price comparison: See .300 Blackout listings and lowest listed cost per round among eligible tracked offers. Check package quantity, observation time, shipping, and tax. Unknown shipping does not establish a delivered-cost winner.
Supersonic ballistics
Compare exact loads separately. This page does not provide a measured supersonic trajectory or barrel-length test series.
Separate 110gr load identities
Shared bullet weight does not establish identical velocity or drag.
Separate 125gr load identities
A match or hunting product-line name does not establish a common ballistic profile. Verify the actual manufacturer's data and stated test conditions for each load separately.
Comparisons with 7.62x39 require exact loads and stated test conditions. Bullet weight alone does not establish ballistic coefficient or a terminal-performance distance. Energy arithmetic is not proof of hunting or defensive effectiveness.
Subsonic ballistics
Verify the exact load's published velocity and test conditions. A catalog velocity does not guarantee subsonic operation in every firearm or atmosphere.
Verify the exact 220gr load
Federal's 2026 law-enforcement catalog identifies AE300BLKSUP2 as 220gr OTM and lists 1,000 fps muzzle velocity. Hornady's 2025 catalog separately identifies item 80877 as 190gr Sub-X. Those specifications do not describe one shared ballistic profile.
This page does not establish a universal effective range or terminal-performance threshold for subsonic ammunition. Trajectory and wind drift require an exact load, velocity, drag model, zero, and atmospheric conditions. Muzzle-energy comparisons alone do not establish tissue or barrier performance.
190gr subsonic (Hornady Sub-X)
The manufacturer's catalog establishes the 190gr Sub-X identity, not a full trajectory. A calculator link without saved inputs does not establish reproducible drop or wind drift.
Verify the exact manufacturer's construction and performance claims for item 80877. This page does not establish that other hollow points fail below a universal velocity threshold or certify hunting or defensive effectiveness.
Barrel length effects
Barrel-length effects depend on the exact load and firearm. This page provides no identified test series establishing a universal powder-burn length or an optimal barrel for either cartridge.
Supersonic loads (125gr)
A valid comparison must identify the same load, barrels, ammunition lots, measurement method, and conditions.
This page does not prescribe a barrel length or establish a universal powder-burn threshold. Barrel comparisons require the same identified load and a documented test protocol; firearm operation and suppressor compatibility require separate verification.
Subsonic loads (220gr)
This page does not establish cycling reliability or an optimal suppressor configuration. Follow the equipment and ammunition manufacturers' guidance; this page supplies no firearm tuning instructions.
A velocity comparison alone does not establish equivalent accuracy, cycling, sound exposure, or terminal performance between barrel and suppressor configurations.
Suppressor performance
A cartridge or subsonic label does not establish a sound-level ranking. Measurements require the exact firearm, load, suppressor, measurement position, and test protocol.
A suppressor does not eliminate muzzle blast or establish hearing safety. NIOSH-hosted research concludes that firearm users should wear hearing protection even when using suppressors. Do not treat an approximate decibel range as permission to omit hearing protection.
Compatibility boundary: Verify the exact cartridge designation and the firearm and suppressor manufacturers' ammunition restrictions before use. A supersonic or subsonic label does not certify equipment compatibility or prevent suppressor damage. This article does not certify any configuration as hearing-safe.
.300 BLK vs 5.56 NATO — ballistic comparison
The cartridges are distinct, not interchangeable ammunition. This page does not assign a universal short-barrel, range, or defensive winner. See the .300 Blackout and 5.56 comparison for exact-load comparison boundaries.
Comparison boundary: You choose the firearm configuration and intended use. This page does not infer those criteria or prescribe a build. Follow the firearm, ammunition, and suppressor manufacturers' guidance; the 5.56 NATO category is not a compatibility authorization.
Related articles
- .300 Blackout and 5.56 comparison
- .300 BLK subsonic loads compared
- 7.62x39 vs 5.56 NATO — AK vs AR caliber comparison
- AR-15 ammo compared
- Subsonic vs supersonic ammo — The fundamentals
- 5.56 ballistic comparison evidence — Exact-load identifiers and calculation boundaries
Related caliber pages
- .300 Blackout ammo prices — Eligible tracked listings
- Lowest observed .300 Blackout prices — Lowest observed prices
- .300 Blackout price history — 30-day pricing trends
Search .300 Blackout by cost per round → | Search .300 Blackout subsonic →
Sources
- Federal 2026 law-enforcement catalog — AE300BLKSUP2 identity and published muzzle velocity
- Hornady 2025 international catalog — Item 80877 identity
- NIOSH-hosted suppressor research — Hearing-protection boundary