The 400 Legend utilizes a 0.4005-inch diameter bullet seated in a straight-walled case to achieve a maximum overall length of 2.260 inches.Factory bullet weights range from 185-grain supersonic hunting rounds to heavy 300-grain subsonic loads.From standard barrels, supersonic muzzle velocities span from 2,250 fps to 2,550 fps, producing up to 2,672 foot-pounds of muzzle energy.Standardized by SAAMI with a maximum operating pressure of 45,000 PSI, it cycles effectively in both bolt-action and AR-15 platforms. To properly stabilize these .40 caliber projectiles, the standard rifle twist rate is 1:16.
400 Legend Specs
| Specification | 400 Legend |
| Cartridge Name | 400 Legend |
| Bullet Diameter | 0.4005 inches |
| Bullet Weight | 185 grains to 300 grains |
| Case Length | 1.650 inches |
| Overall Length | 2.260 inches |
| Base Diameter | 0.422 inches |
| Neck Diameter | ~0.423 inches |
| Rim Diameter | 0.422 inches (Rebated) |
| Shoulder Angle | None (Straight Wall) |
| Maximum Pressure | 45,000 PSI (SAAMI) |
| Typical Twist Rate | 1:16 |
| Typical Barrel Length | 16 to 22 inches |
| Muzzle Velocity | 1,000 fps (Subsonic) to 2,550 fps (Supersonic) |
| Muzzle Energy | ~2,416 to 2,672 ft-lbs (Supersonic) |
| Ballistic Coefficient | ~0.200 to 0.260 (G1) |
| Parent Case | None (New Design) |
| Platform | AR-15, Bolt Action, Single Shot |
| Supersonic Loads | 185 to 215 grains |
| Subsonic Loads | 300 grains |
400 Legend Bullet Diameter
The 400 Legend bullet diameter is 0.4005 inches. Unlike the 350 Legend which utilizes a 0.357-inch bullet, the 400 Legend scales up to a true .40 caliber projectile for a considerably wider permanent wound cavity on large game.
400 Legend Case Length
The 400 Legend case length is 1.650 inches. This specific straight-walled dimension allows the cartridge to comply with restrictive hunting regulations in the American Midwest that completely ban bottleneck cartridges for deer hunting.
400 Legend Overall Length
According to SAAMI standards, the 400 Legend overall length is 2.260 inches. This dimension identically mirrors the 5.56 NATO cartridge, guaranteeing it feeds flawlessly from AR-15 pattern magazines.
400 Legend Bullet Weights
The 400 Legend bullet weights range broadly depending on the application. Standard supersonic factory loads typically utilize 185-grain, 190-grain, or 215-grain bullets, while subsonic options jump all the way to massive 300-grain projectiles.
400 Legend Muzzle Velocity
The 400 Legend muzzle velocity reaches 2,250 fps with standard 215-grain hunting loads.Lighter, premium 185-grain copper bullets can achieve up to 2,550 fps out of a 22-inch barrel.
400 Legend Muzzle Energy
Shooting heavy bullets at high speeds produces exceptional 400 Legend muzzle energy. Factory 215-grain loads generate 2,416 foot-pounds, and 185-grain high-velocity variants can reach an impressive 2,672 foot-pounds of kinetic energy.
400 Legend Maximum Pressure
The 400 Legend maximum average pressure established by SAAMI is 45,000 PSI. This moderate pressure ceiling extends the life of AR-15 bolt lugs and allows for safer operation across various platforms.
400 Legend Twist Rate
To properly stabilize its wide, heavy projectiles, the standard 400 Legend twist rate is 1:16 inches.
400 Legend Barrel Length
The 400 Legend barrel length is highly efficient. While 20 to 22-inch barrels extract maximum velocity, 16-inch barrels still provide sufficient powder burn for effective hunting at mid-range distances.
400 Legend Ballistic Coefficient
Because straight-walled hunting regulations typically require blunt, flat-nose, or rounded projectiles, the 400 Legend ballistic coefficient (BC) is relatively low. The 185-grain copper load features a G1 BC of 0.260, which is excellent for the class but still limits the cartridge to 250–300 yard applications.
Supersonic vs Subsonic
The 400 Legend provides excellent versatility with both high-velocity hunting and suppressor-friendly subsonic options.
| Load Type | Typical Bullet Weight | Velocity | Muzzle Energy | Main Characteristic |
| Supersonic | 185 – 215 grains | 2,250 – 2,550 fps | 2,416 – 2,672 ft-lbs | Flatter trajectory, massive energy transfer on medium game |
| Subsonic | 300 grains | ~1,000 fps | ~660 ft-lbs | Suppressor-friendly, ultra-quiet, extremely heavy projectile |
Because the subsonic 300-grain bullets do not break the sound barrier, they lack the kinetic energy of supersonic loads but excel at close-range suppression.
Factory Load Specifications
When analyzing 400 Legend cartridge specs, factory ammunition data highlights its raw power.
- 185 grain: Bear Creek Ballistics HV (Supersonic). Velocity: 2,550 fps. Muzzle Energy: 2,672 ft-lbs. G1 BC: 0.260 (Tested in 22-inch barrel).
- 190 grain: Winchester Deer Season XP (Supersonic). Designed with an oversized polymer tip for rapid expansion on whitetail deer.
- 215 grain: Winchester Power Point (Supersonic). Velocity: 2,250 fps. Muzzle Energy: 2,416 ft-lbs.
- 300 grain: Winchester Super Suppressed (Subsonic). Jacketed hollowpoint engineered for quiet operation.
Cartridge Dimensions
The 400 Legend dimensions were engineered from the ground up, utilizing a rebated rim design rather than relying on a direct parent case.
| Dimension | Measurement |
| Bullet Diameter | 0.4005 inches |
| Case Length | 1.650 inches |
| Overall Length | 2.260 inches |
| Base Diameter | 0.422 inches |
| Rim Diameter | 0.422 inches (Rebated) |
| Shoulder Angle | None (Straight Wall) |
Barrel Length
The 400 Legend burns powder very efficiently. Velocity loss per inch is roughly 25 fps when reducing barrel length. Chronograph data for the 185-grain HV load demonstrates this efficiency:
- 16 inches: 2,475 fps
- 18 inches: 2,517 fps
- 22 inches: 2,550 fps
Ballistics
Trajectory data for the 215-grain Winchester load with a 150-yard zero:
- Muzzle: 2,250 fps | 2,416 ft-lbs
- 100-yard: 1,872 fps | 1,673 ft-lbs | Drop: +1.8 in
- 200-yard: 1,540 fps | 1,132 ft-lbs | Drop: -4.9 in
- 300-yard: 1,270 fps | 770 ft-lbs
Platform And Compatibility
The 400 Legend does not have a parent case.It shares its 0.422-inch case head dimension with the 6.8 SPC.
- AR-15 Compatibility: To build an AR-15 in 400 Legend, you need a dedicated 400 Legend barrel, a 6.8 SPC bolt face, and a 400 Legend specific magazine.
- Bolt Action: Widely supported in short-action rifles like the Savage Axis and Winchester XPR.
400 Legend vs 350 Legend
| Specification | 400 Legend | 350 Legend |
| Bullet Diameter | 0.4005 inches | 0.357 inches |
| Typical Bullet Weight | 185 gr – 215 gr | 150 gr – 180 gr |
| Muzzle Velocity | ~2,250 fps (215gr) | ~2,250 fps (150gr) |
| Muzzle Energy | ~2,416 ft-lbs | ~1,700 ft-lbs |
| Maximum Pressure | 45,000 PSI | 55,000 PSI |
| Recoil | Moderate | Very Low |
| Primary Design Focus | Maximum straight-wall energy | Low-recoil deer hunting |
The 400 Legend delivers approximately 25% more energy than the 350 Legend, resulting in a vastly superior permanent wound cavity, though it comes at the cost of slightly increased recoil.
Pros And Cons
400 Legend Pros
- Produces 20% more energy than a 30-30 Winchester and 100% more energy than a 12-gauge slug at 100 yards.
- Fully compliant with straight-walled cartridge hunting regulations.
- Integrates perfectly into the AR-15 platform with a simple barrel and bolt swap.
- Capable of deeply penetrating large game like feral hogs and black bears out to 200 yards.
400 Legend Cons
- Ammunition is more expensive and less widely available than legacy cartridges.
- Recoil is noticeably sharper than the 350 Legend.
- Its relatively low ballistic coefficient limits ethical hunting ranges to around 250 to 300 yards.
FAQs
What are the specifications of 400 Legend?
The 400 Legend pushes a 0.4005-inch bullet from a 1.650-inch straight-walled case. Its overall length is 2.260 inches, and it operates at a maximum pressure of 45,000 PSI.
What is the bullet diameter of 400 Legend?
The 400 Legend bullet diameter is 0.4005 inches.
What is the case length of 400 Legend?
The 400 Legend case length is exactly 1.650 inches.
What is the overall length of 400 Legend?
The maximum SAAMI overall length of the 400 Legend is 2.260 inches.
What bullet weights are available for 400 Legend?
Common supersonic bullet weights for the 400 Legend include 185 grains, 190 grains, and 215 grains.Subsonic loads utilize a heavier 300-grain bullet.
What is the muzzle velocity of 400 Legend?
Supersonic 400 Legend muzzle velocity generally ranges from 2,250 fps (215-grain) to 2,550 fps (185-grain). Subsonic ammo is tuned to roughly 1,000 fps.
What is the muzzle energy of 400 Legend?
The 400 Legend muzzle energy is exceptional, sitting between 2,416 and 2,672 foot-pounds.
What is the maximum pressure of 400 Legend?
According to SAAMI, the 400 Legend maximum pressure is 45,000 PSI.
What is the twist rate for 400 Legend?
The standard 400 Legend twist rate is 1:16 inches.
What is the heaviest 400 Legend bullet?
The heaviest commercially loaded 400 Legend bullet is currently the 300-grain Winchester Super Suppressed.
Is 400 Legend subsonic?
Yes, subsonic 400 Legend ammo is available. It utilizes massive 300-grain projectiles loaded to around 1,000 fps to remain extremely quiet when used with a suppressor.
Is 400 Legend supersonic?
Yes, the primary intent of the cartridge is supersonic hunting. Standard factory loads drive 185 to 215-grain bullets at supersonic speeds.
What barrel length is best for 400 Legend?
A 20 to 22-inch barrel provides the maximum velocity potential, but 16 and 18-inch barrels are highly effective for dense brush hunting.
Is 400 Legend compatible with an AR-15?
Yes. To fire the 400 Legend from an AR-15, you must use a dedicated 400 Legend barrel, a 6.8 SPC bolt carrier group, and specialized magazines.
How does 400 Legend compare with 350 Legend?
The 400 Legend is a wider, heavier cartridge. It provides 25% more energy than the 350 Legend, resulting in a much larger wound cavity, but produces moderately more recoil.