Like any gun and cartridge combination, the 300 AAC Blackout has its own personality. Getting to know a few of its character traits can save you a lot of time should things start to act wonky. Let’s take a look at a few of the more common potential gotchas.
Chambering the Wrong Caliber!
You hear internet stories about someone who stuffed the wrong caliber cartridge into a rifle and pulled the trigger. If you’re like me, you take these legends with a grain of salt, shake your head a bit, and move on. Another internet myth right?
Well, this one is true I tell ya! I saw it happen!
I was at my regular outdoor range a month or so back, when I heard a loud bang, closely followed by what can best be described as a “panic shriek.” The scream was intense – kind of like the one Mike Bloomberg makes when he inadvertently stumbles into a Friends of NRA banquet. Looking a few benches to my right, I saw two men, one an experienced shooter, and the other a new shooter, looking dazed and confused. Actually the newer guy was looking more scared and in shock – staring at his hands as if he was surprised they were still attached. Somehow he had stuffed a magazine full of 300 Blackout supersonic cartridges into a 5.56mm rifle, managed to chamber a cartridge, and pulled the trigger.
As you might guess, the gun exploded. Literally. The bolt was bent, upper receiver bulged out, barrel extension trashed, lower receiver trashed and the barrel was now plugged with one very elongated .308 caliber projectile. The shooter was incredibly lucky as much of the pressure escaped through the magazine well. Still, there was enough force in the conflagration to bend a lot of steel and aluminum. The shooter suffered plenty of stinging and mild burns to his hands and face.
Now that I had seen it happen, I became a believer. At least with the right bullet profile, it is possible to fit a 300 Blackout cartridge into a 5.56mm / .223 chamber – at least enough so to allow the rifle to fire. When I got home, I removed an upper from one of my 5.56 ARs and dried dropping various 300 Blackout hand-loaded cartridges into the chamber to see if any would fit. With big and fat bullet profiles, no subsonic loads would come close to fitting, but lighter weight 110 and 125 profiles did in fact come pretty close to fitting in the chamber without application of undue force.
The moral of the story is that it can happen, so be careful when shooting any rifles of similar cartridge design. In this case, it’s doubtful the experienced shooter would have made the mistake, but the new shooter had no idea. Apparently his mentor was paying attention to something else when the shooter loaded the gun.
Fortunately, there are easy ways to minimize the risk. The simplest method is to use magazines of different color for 300 Blackout. Get some tan, dark earth or grey ones. Or you could use metal mags for one caliber and plastic for another. If you already have a supply of magazines, check out MagBands – silicon bands that clearly identify the caliber contained within.