What Happens If You Chamber 300 AAC In a 556 Upper
This video demonstrates the potential consequences of accidentally chambering a 300 Blackout round in a 5.56x45mm NATO upper receiver. The speaker recounts an incident where a 300 Blackout round was found mid-magazine and subsequently chambered in a 5.56 upper. While the round did chamber, it resulted in a light primer strike, preventing a discharge. The speaker emphasizes the importance of careful magazine loading when handling multiple calibers to avoid dangerous ammunition mismatches.











