Ok dumb question, this is my first AR. Failure to eject spent casing question.

[SideShow Bob]

You should never jack around with a new firearm until you are sure that it is functioning properly, you probably voided any warranty by removing the gas block and changing Handguards before even firing it.

This should help you understand how criticle the alignment of gas port in the barrel and gas block are.........

http://www.youtube.com/watch?v=j3ocGn4LD6g

You stated a1/4 in.of movement, the gas ports are anywhere from .081 - .096 in. DIA. And a 1/4 in. Equals .250 in.( up to 3X port size ) You very well could have misaligned the ports.