The barrel and breach were probably scavenged off of a damaged Russian AAA piece, even with plugs and muffs the concussion in that room would ruin your day and probably make your ears ring for the rest of your life.
eta: Russian ZU23 https://encrypted-tbn1.gstatic.com/...wPjwC0TMlx8iCE_TztmQ7X2vIWgcKmjqZctzSt_PSmaww
eta: Russian ZU23 https://encrypted-tbn1.gstatic.com/...wPjwC0TMlx8iCE_TztmQ7X2vIWgcKmjqZctzSt_PSmaww
