Nope, trigger has to come out to make sure that the disconnector spring is installed with the large coil side down into the tail of the trigger.
http://www.ar15.com/content/guides/assembly/lower/
Also, double check the free gap between the disco sear, and the back hammer sear. Hence upper shotgun'd open, don't touch the trigger, then cock the hammer back and get is rear sear aligned with the disco sear. You should have a gap between the two of .001" to .003", hence about the size of a human hair.
If the free gap is huge like the below photo, then either the disco will need to be retimed,the FCG will need to be replaced if the hammer or disco sears are chipped/worn, or you have crap under the front of the disco where it seats against the trigger top surfaces that is holding the disco open instead.