.350 Legend vs .300 Blackout

How do .350 Legend and .300 Blackout compare?

The .350 Legend is a straight-walled cartridge firing a 0.357-inch bullet; the .300 Blackout is a bottlenecked cartridge firing a 0.308-inch bullet. Both have a SAAMI maximum average pressure of 55,000 psi, both share the .223 Remington's 0.378-inch case-head diameter, and both run in AR-15-pattern rifles with a caliber-specific barrel. The .350 Legend was designed for hunting in states that restrict deer cartridges to straight-walled cases; the .300 Blackout was designed to deliver .30-caliber bullets from short barrels, with both supersonic and subsonic loads, and with suppressor use in its design brief.

Live pricing for both sits beside these specifications on the .350 Legend vs .300 Blackout page.

Why does straight-wall vs bottleneck matter?

Several U.S. states limit deer hunting in some zones to rifles chambered for straight-walled cartridges, often in areas that previously required shotguns or muzzleloaders. Winchester designed the .350 Legend for those rules. The .300 Blackout's case has a shoulder, so it does not qualify where a straight-wall rule applies. The specific requirements — which zones, minimum and maximum bullet diameters, and case-length limits — are set by each state and change over time, so the current state regulations are the authority, not the cartridge's marketing.

Outside those rules, the case shape matters mainly for how each cartridge was optimized. The .300 Blackout's bottleneck lets a .30-caliber bullet of 110 to 220 grains sit in a case short enough for standard AR-15 magazines. The .350 Legend uses a longer straight case to reach its velocity with a wider bullet.

What do published loads show for velocity and energy?

Muzzle velocities below are manufacturer-published. Energy is computed as bullet weight (gr) × velocity² ÷ 450,240, and matches each maker's published energy within about one ft-lb.

For supersonic loads, the 180-grain .350 Legend hunting load's computed energy is 1.28 times the 110-grain .300 Blackout load's (1,763 ÷ 1,378), with a bullet 70 grains heavier. The .300 Blackout's subsonic load is a different category: at 1,050 fps it stays below the speed of sound, which removes the bullet's supersonic crack and is the reason the cartridge is common on suppressed rifles. It carries between a quarter and a third of the energy of the supersonic loads in this table.

Velocities depend on barrel length. Many .300 Blackout rifles use barrels of 9 to 16 inches, and manufacturer test-barrel figures will differ from what a given short-barreled rifle produces.

How does recoil compare?

Rifle recoil comes from the bullet and from the powder gas, and powder charges are not published on factory boxes. The computed part here is bullet momentum — bullet weight (gr) × velocity (fps) ÷ 225,218, in pound-seconds.

The 180-grain .350 Legend load produces 1.45 times the bullet momentum of the 110-grain supersonic .300 Blackout load (1.678 ÷ 1.160), and 1.89 times the subsonic load's. In an AR-15 the buffer system spreads that impulse over time, and in either cartridge the momentum is low relative to full-size rifle cartridges such as the .308 Winchester, whose common 150-grain loads exceed 1.8 lb·s on the same calculation.

How do bullet width and sectional density compare?

Two properties can be computed from the specifications alone.

Frontal area. A 0.357-inch bullet has 1.34 times the cross-sectional area of a 0.308-inch bullet ((0.357 ÷ 0.308)²) before expansion. Expanding bullets change both figures after impact, by amounts that depend on bullet design and impact velocity.

Sectional density. Bullet weight (gr) ÷ 7,000 ÷ diameter², in pounds per square inch:

The supersonic loads in each cartridge sit at similar or modestly different sectional densities, while the .300 Blackout's heavy subsonic bullet carries the highest figure in the table at the lowest velocity. Subsonic hunting loads rely on bullets designed to expand at low velocity, such as the Sub-X described by Hornady; at 1,050 fps a conventional rifle bullet designed for 2,000+ fps impacts may not expand as designed. Manufacturers' published terminal-performance data for the specific load is the reference.

Which rifles are chambered for each?

• AR-15 pattern: both cartridges need a caliber-specific barrel; both use the standard AR-15 bolt, because both share the 0.378-inch case head. The .300 Blackout was designed to feed from standard AR-15 magazines. .350 Legend magazines are sold as a separate product, and owners commonly use them.
• Bolt-action rifles: compact bolt actions are offered in both, including Ruger American Ranch versions in each cartridge.
• Single-shot rifles: single-shot hunting rifles are widely offered in .350 Legend for straight-wall hunting zones.
• Pistols and short-barreled rifles: the .300 Blackout is widely used in AR-pattern pistols and short-barreled rifles, which matches its short-barrel design goal.

A caution specific to AR owners: a .300 Blackout cartridge can physically chamber in a 5.56 NATO/.223 Remington AR-15, and firing it there can destroy the rifle. Distinct magazine marking and separate storage are common practices among owners who have both. Each barrel and upper should be checked against the cartridge stamped on it.

What is each cartridge commonly used for?

.350 Legend is commonly used for:

• Deer hunting in states and zones with straight-wall cartridge rules
• Deer and hog hunting at moderate ranges elsewhere
• AR-15 owners who want a hunting cartridge with a wider, heavier bullet than 5.56 offers

.300 Blackout is commonly used for:

• Suppressed shooting with subsonic loads
• Short-barreled rifles and AR-pattern pistols
• Hog and deer hunting with supersonic expanding loads where legal

Criteria a reader can apply:

1. State hunting rules. If a straight-wall rule applies to the zone being hunted, it decides the question; confirm the current rule for that state and zone.
2. Suppressor use. Subsonic options are a defining feature of the .300 Blackout.
3. Barrel length. For very short barrels, compare velocity data published for that barrel length rather than test-barrel figures.
4. Magazines. The .300 Blackout feeds from standard AR-15 magazines; .350 Legend owners commonly use dedicated magazines.

How does cost compare?

This article quotes no prices. Subsonic and premium hunting loads cost more per round than FMJ practice loads in either cartridge, so load type matters as much as the cartridge. Current observed figures are on the .350 Legend ammo prices and .300 Blackout ammo prices pages, and the trend over time on .350 Legend price history and .300 Blackout price history.

Related comparisons

• .300 Blackout vs 5.56 — Two AR-15 cartridges compared
• .300 Blackout vs 7.62x39 — Two intermediate .30-caliber rounds
• .30-30 Winchester vs .308 Winchester — Rimmed lever-action round against a rimless short-action round
• Subsonic vs supersonic — What the speed of sound changes

Related caliber pages

• .350 Legend ammo prices — Current pricing across tracked retailers
• .350 Legend price history — Observed trend over time
• .300 Blackout ammo prices — Current pricing across tracked retailers
• .300 Blackout price history — Observed trend over time

Sources

• SAAMI Cartridge & Chamber Drawings — Dimensions and maximum average pressure for .350 Legend and .300 AAC Blackout
• Winchester Ammunition — .350 Legend design brief, USA 145gr FMJ and Super-X X3501 published velocity and energy
• Hornady — BLACK 110gr V-MAX and Subsonic 190gr Sub-X (item 80877) published velocity and energy
• American Rifleman — Tested: Winchester's 350 Legend — Case-head dimensions relative to .223 Remington