Okay, so it isn’t terrible exactly. Not in the sense that leaving a bottle of lotion on the coffee table and playing “Goodbye Horses” is a terrible way to impress a date, but it also isn’t what most of the breathless fanbois are fainting over, either. A big part of the attraction to having .300 Blackout is to put a silencer on it and feel super operator pew-pewing subsonic ammo. There is no argument that shooting a quiet rifle is a lot of fun, but fun does not stop bad men from doing bad things and subsonic bullets don’t do a great job of stopping them, either.
It really should not come as any surprise that when you slow a bullet down to pistol velocity it produces a pistol like wound. Now, to be explicitly clear, this load is not intended for defense. It is designed to hunt hogs discretely so as not to spook cattle. It does that very well. It is the only .30 caliber bullet that I have seen which can expand at subsonic velocity. It cuts a respectable path through the gelatin for a .30 caliber pistol bullet, but let us be crystal clear: for all intents and purposes, that is a pistol bullet.
In this perspective, a rifle loaded with subsonic .300 Blackout may as well be a pistol caliber carbine. PCCs may seem like a good idea at first glance, but when you get down to brass tacks they offer all of the disadvantages of a rifle (too large to conceal or carry conveniently and not easily operated with one hand) with the primary disadvantage of a pistol (weak ammunition). Not only does subsonic ammunition perform far more poorly in tissue, it also gives up one of the other primary advantages of a rifle: the ability to penetrate soft body armor.
Crooks are wearing body armor more frequently when committing home invasions and soft armor can be found in many pawn shops or online for less than you might think. It may not be a high probability, but the point isn’t that you must be able to penetrate armor. The point is that if you are going to choose a rifle sized weapon, you ought to use ammunition that can do rifle sized work. What about supersonic .300 Blackout, you say? It is absolutely true that supersonic .300 Blackout is every bit as effective as other intermediate rifle cartridges such as 5.56mm or 7.62x39mm.
You can see that it absolutely does a fantastic job, even coming out of an 8” barrel. It offers good penetration, expansion, and a respectable stretch cavity. In that regard, there is nothing necessarily wrong with .300 Blackout. At least, if you only consider the technical ability of the cartridge without considering cost. If you are looking to purchase a home defense rifle, .300 Blackout may not be a terrible choice, so long as you use full power ammunition. But if you are one of the many folks considering converting one of your 5.56mm rifles to .300 Blackout, it makes somewhat less sense. Supersonic .300 Blackout does nothing that supersonic 5.56mm, 7.62x39mm, 6.8mm, or 5.45mm can’t do and subsonic .300 Blackout is a poor choice for defense. While ammunition is becoming more widely available, there is nowhere near the selection and availability as there is for .223 Rem or 5.56x45mm.
Perhaps one of the most sobering problems with .300 Blackout is the ability to chamber in a .223 or 5.56mm barrel. While the bullet is obviously much larger, the parent case is 5.56mm so it will fit into the chamber. The bolt won’t close on a .300 Blackout round if it is closed slowly, but if the round has low neck tension, the momentum of the bolt carrier can force the bullet back into the case, allowing the bolt to close and lock. Remember, one of the main selling points of the .300 Blackout is that all of the parts are the same as your 5.56mm rifle, except for the barrel. Obviously the results of firing a round in this manner would be catastrophic. This presents little problem if you do not already own a 5.56mm rifle, but it seems fair to wager that the majority of prospective .300 Blackout owners also own AR-15 type rifles chambered in 5.56mm.
Someone once told me that .300 Blackout is the most convenient way to shoot 7.62x39mm in an AR type rifle. That is probably the most succinct way to sum up what .300 Blackout is. 7.62x39mm is a respectable cartridge and so is .300 Blackout… when it is loaded to supersonic velocity. While neither are well suited for long range shooting, they are more than adequate at close to medium range. The problem is that there are quite a few folks out there that just cannot seem to understand that a rifle bullet that is no longer moving at 2,000 fps, give or take, is not really much of a rifle bullet any more. To be fair, .300 Blackout is not actually terrible in its own right, it is just that the primary purpose for having one is to shoot subsonic ammunition and subsonic ammunition really is terrible for defense.
Andrew Betts served with the Arizona National Guard for over 12 years, including a tour to Afghanistan. Visit his YouTube Channel for more great shooting information.