I have my M&P 15 pulled apart. Got the charging handle and bolt out; but, can't seem to get them back in. I can get the handle in by itself to where it latches; try to put them in together and no luck. The back end of the bolt assembly appears to stick out too far, so the upper/lower parts won't fold back together. Would anyone understand and know what I'm doing wrong?

How far? A half inch like the bolt lugs won't go into the barrel or a few inches like the bolt cam is catching on the side of the upper?