I went shooting with a friend this weekend and we were shooting his ar and it would fire but failed to eject the spent case unless you remove the mag and thin it would remove that case. i am new to ar's and so is he what could be the problem? The gun is clean.
we were only loading 1 round into the magazine after we discovered the issue. after the shot, the spent brass would be left in the chamber and the slide would lock back. if you release the slide and pull the charging handle again, the brass ejects every time. let me know if i need to give more details. this ar has maybe 150 rounds through it total.
I am certainly no expert but I would try either a new extractor or possibly an extractor upgrade kit from a place like bravo company. You could probably start out using the upgrade insert and spring first, then try using the o-ring as well if you continue to have problems. If the rifle is locking back with the empty mag it does not sound like a short stroke issue.