One of the huge draws of the 300 AAC Blackout (AKA 300 BLK) is that it can use the same bolt and magazines as a .223/5.56 AR-15. The only downside? It can use the same bolt and magazines as the .223/5.56 AR-15.

A friend and reader presented me with a box of AR-15 upper receiver parts this past weekend that vividly illustrates what happens when a distracted or negligent person loads magazines.

A single 300 BLK cartridge somehow found it’s way into a box of loose .223 cartridges, and was subsequently loaded into a 30-round PMAG, which was then handed to an AR-15 shooter shooting a rifle chambered in .223 Wylde (a chambering that is supposed to shoot both .223 Remington and 5.56 NATO equally well).

The .223 cartridges in the magazine went “bang-bang-bang.” The 300 Blackout round apparently fed into the chamber just fine, the shooter pulled the trigger, and what you’ll see on the following pages were the result of the ensuing kaboom.

Luckily, the shooter was shaken, but uninjured.

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