Testing .300 Blackout Ballistics
.300 Blackout is a relatively new cartridge with a unique history. The caliber is a result of the military’s experience using the 5.56mm round in M16. .300 Blackout was specifically designed to work well with the M4/AR15 style of guns. The round is built on the tried and true .223 cartridge but with a wider neck that allows it to accept .30 caliber bullets. As a result, .300 Blackout ballistics are very similar to the 7.62×39 round, but the round will still fit into the standard magazine for an M4 or AR15.
However, the.300 Blackout round (or 300BLK for short) can serve two roles. 300BLK has supersonic bullet speeds when loaded with lighter bullets in the 120 to 130 grain range. This means that while the sound of the round firing is quieter when using a suppressor, there is still a very loud “crack” when the bullet breaks the sound barrier. 300 Blackout is designed to use heavier bullets in the 190-230 grain range which travel at subsonic velocities, yet still work well in the M4/AR platform.
Our test gun, a 300 Blackout pistol with a 10.5 in barrel.
That’s quite the technological achievement. The vast majority of AR style guns use either a direct impingement or gas piston system to cycle the action and chamber a new round. These systems are designed to work with a specific range of energy. That energy is delivered to them from the gases siphoned off by each round firing. Too much gas siphoned off (and too much energy delivered to the action results in feeding issues and low muzzle velocity. Too little gas siphoned off, and the AR doesn’t have enough power to load a new cartridge. What the creators of the 300 Blackout managed to do is create a round that delivers enough energy to work reliably in an AR with both high-speed, supersonic rounds and heavier, slower-speed subsonic rounds.
Subsonic 300 Blackout Ballistics Test
It’s that last type of rounds that we’ll be testing today. Subsonic .300 Blackout rounds are a bit of an outlier in the world of rifle ammunition. As they don’t break the sound barrier when fired, they are quieter to shoot than supersonic ammunition. At around 220 grains, subsonic 300 Blackout ammo weighs about as much as .45 ACP, and travels about as fast as .45 as well. However, they have a shape that is much more aerodynamically efficient than .45 ACP, which allows them to fly more accurately and retain more energy at longer distances than .45 ACP typically does. What’s missing, though, is any indication of what a subsonic .300 Blackout round does when it hits the target, and that will play a big part in our test of .300 Blackout subsonic ballistics.
Testing Protocol
We’ll be testing four different kinds of subsonic .300 Blackout ammo. Two of the rounds have a polymer tip that is designed to open up and slow down the round on impact. One of the rounds uses open-tip match (OTM) bullets, and one is a conventional full metal jacket round. We’ll be shooting five rounds of each through four layers of heavy cloth into Clear Ballistics gel, an industry standard testing medium.
The gun we will be using is a .300 Blackout pistol with a 10.5 inch barrel and a 1 in 8 twist rate. We will be measuring the muzzle velocity of each round using a ProChrono Digital PAL chronograph set up at the muzzle, and then plug that data into Strelok Pro in order to work up some ballistics charts for each round.
Ammo Tested
Federal American Eagle Suppressor
Bullet Weight: 220 Grains
Bullet Type: Open Tip Match
Avg. Muzzle Velocity: 990 fps
Avg. Muzzle Energy: 472 ft/lbs
Bullet Drop at 50 yds: 0.77 inches
Bullet Drop at 100 yds: 9.22 inches
Energy at 100 yards: 453 ft/lbs
Bullet Drop at 200 yds: 54.27 inches
Energy at 200 yards: 430 ft/lbs
Average Penetration Depth: 13.54 inches
Expanded Bullet Diameter: N/A
Expanded Bullet Weight: N/A
Notes: Penetration measured at exit point of bullets from gel blocks
Hornady Sub-X Subsonic
Bullet Weight: 190 Grains
Bullet Type: Polymer Flex Tip
Avg. Muzzle Velocity: 1026 fps
Avg. Muzzle Energy: 443 ft/lbs
Bullet Drop at 50 yds: 0.64 inches
Bullet Drop at 100 yds: 8.49 inches
Energy at 100 yards: 405 ft/lbs
Bullet Drop at 200 yds: 51.47 inches
Energy at 200 yards: 375 ft/lbs
Average Penetration Depth: 18.94 inches
Expanded Bullet Diameter: 0.54 inches
Expanded Bullet Weight: 189.6 grains
Notes: Only ammo tested to have all five rounds stay in the gel
Hornady Black Subsonic
Bullet Weight: 208 Grains
Bullet Type: A-Max Polymer Tip
Avg. Muzzle Velocity: 965 fps
Avg. Muzzle Energy: 468 ft/lbs
Bullet Drop at 50 yds: 0.7 inches
Bullet Drop at 100 yds: 8.78 inches
Energy at 100 yards: 442 ft/lbs
Bullet Drop at 200 yds: 52.22 inches
Energy at 200 yards: 419 ft/lbs
Average Penetration Depth: 14.8 inches
Expanded Bullet Diameter: N/A
Expanded Bullet Weight: N/A
Notes: Penetration measured at exit point of bullets from gel blocks
Sellier & Bellot 300 Blackout Subsonic
Bullet Weight: 200 Grains
Bullet Type: Full Metal Jacket
Avg. Muzzle Velocity: 930 fps
Avg. Muzzle Energy: 384 ft/lbs
Bullet Drop at 50 yds: 1.18 inches
Bullet Drop at 100 yds: 12.18 inches
Energy at 100 yards: 310 ft/lbs
Bullet Drop at 200 yds: 72.52 inches
Energy at 200 yards: 256 ft/lbs
Average Penetration Depth: 16.28
Expanded Bullet Diameter: N/A
Expanded Bullet Weight: N/A
Notes: Penetration measured at exit point of bullets from gel blocks
300 Blackout Ballistics Test Results
As a comparison, a 230 grain round of Federal JST .45ACP ammunition has a muzzle velocity of 863 fps and has 380 ft/lbs of energy at the muzzle when fired from a 1911. At 200 yards, the 60.5 inch bullet drop of a .45 round is similar to a .300 Blackout subsonic round. However, the energy of the .45 at that distance is much less, only 236 ft/lbs. On the other hand, a supersonic .300 Blackout ammo such as the 124 grain Sellier & Bellot round has a muzzle velocity of 2165 fps and 1285 ft/lbs of muzzle energy,
Gel Test Results
We were able to recover two rounds from the range, one each of the Hornady Black and Federal ammo.
The different reactions of each bullet to impacting the gel are very interesting. Three of the rounds we tested immediately destabilized and traced swooping arcs through the ballistics gel. The rounds then left the gel in random directions, including punching holes in the table that supported the gel. Every round of the Hornady Sub-X round, on the other hand, stayed in the gel as it expanded. We were able to recover and measure all five rounds we shot into the gel. We found one round of the Sellier & Bellot ammo and one round of the Hornady Black ammo underneath the table that held the shooting gel. No examples of the Federal ammunition were recovered.
Only the Hornaday Sub-X rounds stopped within the gel.
The different behavior of the Hornady Sub-X round versus the others comes down to the shape of the bullet. The Federal, Sellier & Bellot and Hornady Black rounds are all spitzer bullets and have sharply sloped noses. When these bullets hit the testing gel, they quickly destabilized and caused dramatic cavities inside the gel. The short, blunt tip of the Hornady Sub-X round, on the other hand, is more commonly associated with pistol bullets, and that resulted in results that mimicked the results we’ve seen from pistol rounds fired into this testing medium.
Is 300 BLK A Good Choice for Defense?
Based on these results, I would have no problem using any of the rounds in a defensive firearm. They all reached the minimum 12 inches of penetration through heavy cloth. The Hornady Sub-X rounds expanded and came to a stop, while the other rounds tumbled in the gel, causing damage as they changed course. A subsonic .300 round is nowhere near as powerful as faster supersonic round of the same ammunition. However, based on our testing, they do have enough power to deliver the goods when it matters the most.
