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Hornady Subsonic 300 Blackout 190 Gr Sub-X

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Ammo Reports Team 7 300 Blackout

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Official Specs

Note: Hornady does not publish muzzle energy for this load on their official product page. Muzzle energy calculated from the stated 1,050 fps and 190 gr bullet is approximately 464 ft-lbs — this figure is derived and labeled as such in the ballistics table below, not a manufacturer-stated value.

Note: Ballistic coefficients (G1 and G7) are not published by Hornady for the Sub-X projectile in this configuration. Until manufacturer data is available, BC values are omitted rather than estimated.

Note: UPC was not available from the product data provided. If you have a verified UPC, community submission is welcome.

Hornady Subsonic 300 Blackout 190 Gr Sub-X (Box)

$37.49

$44.99

in stock

Ballistics Table

Calculated estimate. Real-world results vary by barrel length, temperature, altitude, and lot. Community submissions will provide measured muzzle velocity for comparison.

Calculation basis: 190 gr bullet, muzzle velocity 1,050 fps (Hornady 16″ barrel), estimated G1 BC ≈ 0.270 (derived from comparable heavy subsonic .30-cal bullets — treat as approximate). Zero: 100 yd. Sight height: 1.5″ above bore.

Key takeaway: At subsonic velocities, the 190 gr Sub-X sheds energy and speed quickly beyond 200 yards — the trajectory drop of over 38 inches at 300 yards makes holdover compensation essential at extended range. This load is purpose-built for short-to-medium range engagements, generally inside 200 yards, where its primary advantages — low noise signature, deep penetration, and controlled expansion — are most relevant. For suppressed hunting applications, the practical ethical hunting range on medium-sized game is best kept within 150–200 yards. The heavy bullet retains meaningful energy through 200 yards for deer-sized targets when shot placement is precise.

The Sub-X Bullet: Why the Design Matters

The Hornady Sub-X projectile is not a conventional hunting or target bullet adapted for subsonic use — it was engineered specifically for the velocity range below the speed of sound. Standard expanding bullets often fail to reliably expand at subsonic velocities because they depend on hydraulic pressure generated at higher impact speeds. The Sub-X addresses this with a Flex Tip insert seated in the bullet’s hollow point cavity. On impact, the elastomeric tip is driven rearward into the lead core, initiating and sustaining expansion even at velocities in the 900–1,050 fps range.

The longitudinal grooves machined into the gilding metal jacket serve two functions: they reduce bearing surface contact with the bore (which can lower pressure and improve consistency at subsonic charge levels), and they act as predetermined fracture lines that guide the jacket’s petal formation during expansion. The result is a bullet designed to expand reliably, retain significant weight, and penetrate deeply — characteristics that matter most when terminal velocity is already limited by the subsonic constraint.

This design philosophy distinguishes the Sub-X from the open-tip match (OTM) bullets used by most competing subsonic 300 Blackout loads. OTM bullets are optimized for accuracy, not terminal performance, and their expansion behavior at subsonic velocities is inconsistent and largely incidental. Hunters selecting a suppressed 300 Blackout load specifically for taking game will find the Sub-X’s intentional terminal design more appropriate than a match bullet repurposed for the role.

Best Uses

Good fit:

• Suppressed hunting of deer, hogs, and similarly sized game inside 150–200 yards
• Tactical and home-defense applications where sound reduction is a priority and a suppressor is in use
• Range training with a suppressor where maintaining subsonic velocities is required for noise management
• Semi-automatic platforms (AR-15 with 300 BLK upper, pistol-length or rifle-length) configured for subsonic cycling
• Situations requiring a controlled-expansion bullet rather than a match-grade OTM in a subsonic role

Not the right tool for:

• Unsuppressed use — the subsonic load offers no meaningful noise advantage without a suppressor
• Long-range engagements beyond 200 yards, where the trajectory drop becomes difficult to manage and energy levels drop significantly
• Targets requiring deep penetration through heavy bone or barriers, where a heavier or harder projectile may be more appropriate
• Firearms with short barrels (under 9 inches) where cycling reliability with subsonic loads may be inconsistent without tuning
• Supersonic applications — this load is not designed to, and will not, exceed the speed of sound under standard conditions

Reliability Notes

No structured submissions yet.

Based on manufacturer claims and open-source user reports, the following observations are noted — these come from manufacturer documentation and publicly available discussion, not structured AmmoReports data:

• Hornady states this load is designed to function in semi-automatic platforms with standard 300 Blackout gas systems, though users on public forums report that some short-barreled pistol-length builds may require adjustable gas blocks for reliable cycling with subsonic loads generally
• The Flex Tip insert is reported by Hornady to initiate expansion consistently at velocities as low as subsonic impact speeds, though independent gel testing data from third-party sources varies by platform and distance
• Brass cases are reported to be consistent in dimension and primer pocket depth, which is relevant for users who intend to reload spent brass after initial firing
• No active recalls or safety notices were identified for this load at the time of publication

Competitors

Note: The majority of competing subsonic 300 Blackout loads use OTM bullets designed for accuracy rather than terminal expansion. The Sub-X is one of the few factory subsonic loads in this caliber using a bullet specifically engineered for controlled expansion at subsonic velocities.

Price Reality

• Typical retail range: $32–$38 per 20-round box; case pricing (typically 10 boxes/200 rounds) runs approximately $320–$370 when available
• Per-round cost: approximately $1.60–$1.90 depending on retailer and timing
• Compared to Fiocchi 300 BLK 220 gr OTM Subsonic (~$25–$30/box), the Sub-X carries a $5–$10 per box premium — justified if terminal performance on game is the priority
• Compared to SIG Sauer Elite 300 BLK 220 gr OTM (~$28–$34/box), the price difference is smaller and primarily reflects bullet design differences
• Compared to Barnes TAC-TX 300 BLK 110 gr (~$38–$44/box), the Sub-X is comparably priced but serves a different role (subsonic vs. supersonic)
• Fair price benchmark: At the $34.99 reference price, this load is competitively positioned for a purpose-designed subsonic hunting round. Prices above $42/box for a 20-round box of this specific load should be considered elevated and worth shopping around

Prices change. Check the Where to Buy block for current listings.

Where to Buy

Hornady Subsonic 300 Blackout 190 Gr Sub-X (Box)

Experience the ultimate in low-noise shooting with Hornady Subsonic 300 Blackout 190 Gr Sub-X ammunition, engineered for precision and minimal sound. Its unique Sub-X bullet design ensures high-impact performance while maintaining stealth, making it an ideal choice for tactical situations and hunting.

$37.49 at Ammunitiondepot.com

Affiliate links. These do not influence ratings, data, or any editorial content on this page.

FAQ

Does the Sub-X bullet actually expand reliably at subsonic velocities, or is this a marketing claim?

The concern is legitimate — most conventional hollow point bullets require impact velocities above 1,800 fps to expand consistently, and subsonic loads operate well below that threshold. Hornady’s Sub-X uses a Flex Tip insert that mechanically initiates expansion on impact regardless of velocity, functioning similarly to the FTX bullet used in their LEVERevolution line. Independent gel tests from several firearms media sources have shown measurable expansion from the Sub-X at subsonic impact velocities, though petal consistency varies. This does not mean performance is guaranteed in all conditions — shot placement and target density still matter significantly at these velocities.

How does this load compare to the Hornady BLACK 300 BLK 208 gr A-MAX for suppressed hunting use?

Both are Hornady subsonic loads in 300 Blackout, but they serve different priorities. The 208 gr A-MAX (used in the BLACK line) is an open-tip match bullet optimized for long-range accuracy — its terminal behavior at subsonic velocities is inconsistent and not designed for hunting. The 190 gr Sub-X sacrifices a small amount of the A-MAX’s ballistic coefficient in exchange for a bullet specifically engineered to expand and penetrate on game. For hunting applications, the Sub-X is the more appropriate choice between the two.

Is this load safe to use in a 300 Blackout pistol-length build without a suppressor?

The load is safe to fire in any 300 Blackout chambered firearm in good working condition, with or without a suppressor. However, two practical points apply: first, without a suppressor, there is no meaningful noise reduction advantage over supersonic loads — the muzzle blast from an unsuppressed firearm dominates regardless of whether the projectile is subsonic. Second, short-barreled pistol builds (under approximately 9 inches) may experience reduced gas port pressure with subsonic loads, potentially causing short-cycling in semi-automatic platforms. An adjustable gas block is often recommended for reliable function with subsonic ammunition in these configurations.

What game animals is this load appropriate for, and at what distances?

The 190 gr Sub-X is most appropriately matched to deer, hogs, coyotes, and similarly sized game at distances inside 150–200 yards. At 100 yards the load retains approximately 389 ft-lbs of energy (calculated), which meets minimum energy thresholds recommended for deer-sized game in most guidelines, though shot placement becomes more critical than with a higher-energy supersonic load. Beyond 200 yards, trajectory drop and energy loss make ethical shot placement increasingly difficult, and this load should not be considered appropriate for hunting at those distances. It is not recommended for elk, bear, or other large or dangerous game where deep penetration through heavy bone and muscle mass is required.

Will this ammunition cycle reliably in a standard AR-15 upper converted to 300 Blackout?

Compatibility depends on the specific gas system configuration of the upper. A properly configured 300 Blackout upper with a rifle or mid-length gas system tuned for subsonic loads should cycle this ammunition reliably. However, many AR-15 builds converted to 300 Blackout retain gas systems tuned for supersonic pressures, which can result in under-cycling (failure to eject or feed) with subsonic loads. Hornady designs this load to function in standard 300 Blackout semi-automatic platforms, but users experiencing reliability issues should first try an adjustable gas block before concluding the ammunition is at fault.

Hornady Subsonic 300 Blackout 190 Gr Sub-X (Box)

$37.49

$44.99

in stock