Yes the hole is for gas to escape if the case fails
Thanks for the reply.   

  I was figuring it was for that, but wasn't sure.    
The barrel marking thing isn't a big deal, but it does look nasty (pics don't show it clearly).  More like someone just wacked the barrel with a cheap marking tool and didn't do it right.   

  The other markings on the barrel look professional and even.
More importantly, the rifle shoots great and is reliable.