A don't ride the charging handle back forward.  You need to pull all the way back on the charging handle, then let it go.  When the bolt is correctly locked up, the front face of the carrier will be tight against the back face of the barrel extension.


Next, shotgun the upper open, and pay close attention to the hammer spring.  The legs of the spring should be coming out from the bottom of the coil and on top of the hammer pin.

http://www.ar15.com/forums/t_3_66/241858_New_Trigger_and_hammer_pins_walking_out__Why_my_rifle_is_not_igniting_the_primer_.html

Lastly, before you take the rifle out again, make sure to correctly clean in, including using a chamber brush with CLP by hand, then make sure to correctly CLP lube it.  If needed, we have a entire forum on cleaning and lubing the rifle correctly if needed.   And when you are cleaning, make sure to pull down the mag and CLP clean them as well.