All in Favor of a 300 Blackout Pistol

   12.19.19

The 300 Blackout is particularly well-suited to pistol configurations. Rifles in the same caliber are also cool and make good multi-purpose guns, but if you’re going to choose a full-rifle configuration, you have a lot of caliber options available for different purposes. Want more short to medium range “oomph?” try a 6.8 Remington SPC. long range, then consider a 6.5mm in the AR-10 platform or perhaps .224 Valkyrie on the AR-15 chassis.

The value of the 300 Blackout boils down to two factors. First, compared to the .223 Remington, you’re launching a larger caliber and heavier bullet at supersonic speeds. Second, you have the flexibility to go slow and heavy with subsonic rounds in the 220-grain (or heavier) weight class. Hold that thought—there are some pros and cons to having that flexibility.

I configured this SAINT Victor 300 Blackout pistol with a Trijicon 3-30 ACOG scope. It's a perfect combination for short to medium range use.
I configured this SAINT Victor 300 Blackout pistol with a Trijicon 3-30 ACOG scope. It’s a perfect combination for short to medium range use.

To explore these angles, let’s consider the Springfield Armory SAINT Victor 300 Blackout pistol. This compact AR-15 package sports a nine-inch barrel, which is an inch and a half longer than its 5.56mm counterpart.  If you do the math on that, you’ll find that adding a suppressor in the seven-inch range puts you pretty darn close to the overall “barrel” length of a standard AR-15 rifle. So, you opt for a short and compact pistol or a suppressed firearm that isn’t any longer than an unsuppressed one. Of course, the suppressor will add a pound, give or take, to your overall weight, and that will affect handling when using the brace. Overall, this pistol measures 27.75 inches long and weighs in at 5 pounds, 9 ounces unloaded.

Speaking of the pistol brace, this one sports an SB Tactical SBX-K model. It’s a little shorter than the original and measures 6.2 inches. It’s a universal fit model, so it will mount to any standard AR pistol buffer tube with a diameter between 1.1 and 1.25 inches. It’s made of some sort of rubber or silicone, so it has some flex. Like other models, you put your forearm through it and tighten a Velcro strap to secure. Although it’s made by SB Tactical, you will note a nifty Springfield Armory logo stamped into the side.

The SB Tactical SBX-K brace is slightly pliant and uses a Velcro strap for security. It's a fixed-position configuration.
The SB Tactical SBX-K brace is slightly pliant and uses a Velcro strap for security. It’s a fixed-position configuration.

Like other Springfield Armory AR rifles and pistols, this one uses forged Type III Hard Coat Anodized, 7075 T6 Aluminum upper and lower receivers with the Accu-Tite system. That allows you to precisely fit the upper and lower for a no-shake or rattle configuration. The handguard is a Springfield model with M-LOK attachment slots and a short rail segment up front for a backup iron sight. There is a hand stop on the lower front end of the handguard—a great feature for a short rifle. Besides providing some grip placement consistency and stability, it prevents you from getting fingers up in the muzzle and flash hider area.

The trigger is a flat profile, nickel boron-coated design that operates in single-stage mode. After somewhere between 2/16ths and 3/16ths of an inch of travel, it breaks cleanly right at five pounds. It’s definitely superior to standard mil-spec triggers. The trigger is protected by an enlarged Bravo Company Mod.3 trigger guard that’s spacious enough for gloved use.

The Nickel-Boron treated flat trigger is crisp and clean and breaks at exactly five pounds. Perfect for defensive use.
The Nickel-Boron treated flat trigger is crisp and clean and breaks at exactly five pounds. Perfect for defensive use.

One benefit of the 300 Blackout offering is its near-complete compatibility with .223 Remington AR components. With a simple barrel swap, everything else in an AR-15 rifle or pistol platform remains identical. So it’s no surprise that the SAINT Victor ships with a standard magazine that pack 30 rounds.

To run through some of the testing and ballistics that we’ll cover in a minute, I mounted a Trijicon ACOG 3-30 Riflescope. This unit features fixed 3x magnification, and a reticle optimized for 300 Blackout use—more on that later. The 3x power setting is perfect for short to medium range use. With both eyes open you have a great field of view and the magnification isn’t enough to interfere with short-range use, even ultra-close indoor distances.

I did some shooting from the bench to check out this setup. Considering it’s a pistol configuration, I did accuracy testing at 50 yards instead of 100. To measure average velocity, I used a Shooting Chrony Beta Master Chronograph 15 feet in front of the bench. Here’s what I found with a few different types of ammo.

Ammo Average Velocity (fps) Five-Shot Group, 50 yards
Sig Sauer Supersonic 300 AAC Blackout 125-grain 2,106.7 1.27”
Inceptor SRR 300 AAC Blackout 88-grain 2,459.3 1.42”
American Eagle Suppressor 300 AAC Blackout 220-grain 1,043.0 1.29”

Where I live, the average temperature range puts the speed of sound right at 1,130 feet per second, give or take, so the subsonic loads were comfortably out of range of supersonic cracks. Even without a suppressor in place, those were quiet.

If you’re considering an AR rifle or a 300 Blackout pistol, there are a couple of points to understand.

Got Gas?

One of the challenges of building a firearm that runs both supersonic and subsonic ammo is having the right amount of gas. The port diameter and placement have to balance perfectly with the buffer and recoil spring in order to assure reliable extraction and feeding but without excessive bolt velocity.

The handguard is slender and features M-LOK attachment points. Note the short rail segment up front for backup iron sight use.
The handguard is slender and features M-LOK attachment points. Note the short rail segment up front for backup iron sight use.

Actually, it’s more complex than that. Especially if you’re considering using subsonic ammo, a suppressor makes a lot of sense. The problem is that adding a suppressor changes the gas flow dramatically, so any optimization done to make sure all sorts of fast and slow ammo work without a suppressor falls out the window when you add a suppressor. If you’ve shot an AR-type firearm with a suppressor, you know that every shot comes with a free hot and dusty powder facial treatment, free of charge. That’s because the suppressor’s job is to capture and slow down all that hot gas exiting the muzzle. Since it can’t all move forward and out the muzzle unhindered, some comes straight back into the action and at you. That’s why suppressed semi-automatic rifles get so filthy and those unfired rounds in the top of your magazine acquire a nice coating of gunk. So, the 300 Blackout firearm design goals look something like this:

  • The firearm has to cycle reliably, but not too fast, when shooting supersonic ammo unsuppressed.
  • The firearm has to cycle reliably, but not too fast, when shooting supersonic ammo with a suppressor attached.
  • The firearm has to cycle reliably when shooting subsonic ammunition unsuppressed.
  • The firearm has to cycle reliably, but not too fast, when shooting subsonic ammunition suppressed.

Here are the gotchas: If you tune the gas system so that the pistol fires with enough gas pressure to reliably cycle the action in all scenarios, you risk beating up your gun when shooting suppressed. That’s because there’s more back pressure coming through the system to speed up the recoil sequence. On the other hand, you have to allow enough gas flow so that subsonic ammo, with its far lower operating pressure and gas volume, will still run the action. When shooting subsonic ammo with a suppressor, you get some help in that department from the backpressure created by the silencer.

One benefit to the pistol (or short-barreled rifle) platform for 300 Blackout is that they use a pistol-length gas system. With the gas port located closer to the receiver, the system does a better job of functioning with low gas volume scenarios like shooting subsonic ammo.

There is a handstop on the bottom leading edge of the handguard. This is a great safety feature and helps with consistent hand placement.
There is a handstop on the bottom leading edge of the handguard. This is a great safety feature and helps with consistent hand placement.

Point of Impact and Optics Considerations

Being able to shoot supersonic and subsonic ammunition simply by inserting a new magazine sounds great—on paper. In fact, it is great. You just need to plan for it in advance by understanding your points of impact relative to the points of aim offered by your optic.

Those supersonic 110 and 125-grain 300 Blackout loads have very different trajectories than the 220-grain (or heavier) subsonic bullets. The slow movers tend to fly more like VW busses. At very close range, this isn’t a big deal. At 50 yards or more, you need to plan for very different points of impact between the two types of ammo. With a 100-yard zero for the supersonic ammo, you can hold the crosshairs right on target when shooting the fast stuff, but you must hold over if you switch to subsonic.

The SAINT Victor pistol shown here is currently equipped with a Trijicon ACOG 300 Blackout optic. It’s perfect for this application because the reticle is designed specifically to solve this problem. You zero your supersonic load at 100 yards using the traditional crosshairs. Then, in theory, you use two thick dots below that on the vertical stadia for point of aim for subsonic ammo at 50 and 100 yards. I’ve tested this with standard 125-grain supersonic ammunition and 220-grain subsonic, and it works within minute-of-paper-plate accuracy.

The handguard does have a small receiver rail extension in case you need to mount an optic slightly forward of the receiver.
The handguard does have a small receiver rail extension in case you need to mount an optic slightly forward of the receiver.

I zeroed the SAINT Victor pistol at 50 yards for supersonic ammo. On a whim, I shot both supersonic and subsonic ammo and found that both impacted darn close to the bullseye at 50 yards. If you’re going to shoot primarily at shorter ranges with the subsonic, perhaps a 50-yard zero for the supersonic option makes sense. I’m definitely going to experiment with this setup more to see how the reticle maps to subsonic point of impact at 25, 75, and 100-yard ranges.

Summing it Up

If short and compact is the goal for your AR platform firearm, a pistol format makes a lot of sense. There’s nothing wrong with a .223 Remington / 5.56mm NATO offering, but you do lose some of the effectiveness of the .223 round, which relies on high velocity for its terminal performance. Near the 3,000 feet per second velocity band, 5.56mm full metal jacket projectiles will fragment and tumble, depending on the design. At lower velocities when fired from a shorter-barrel pistol, those same projectiles are more likely to make small holes.

The 300 Blackout, on the other hand, launches a bullet that not only carries a significantly larger frontal area, the standard projectiles are approximately double the weight. The most common supersonic loads range from 110 to 125-grains. Compare that to 55 to 77 for .223 Remington.

You’ll pay more for ammo, but if your intended use case is defensive in nature, it may be a worthwhile tradeoff.

Read More