Welcome to the forum. Sounds like it is feeding, but not fully chambering? Could be a parts fitment issue, could be a tight chamber, or out of spec ammo.

Does the rifle go into battery reliably when the bolt is closed on an empty chamber? When it fails to go into battery with a 5.56 round, can you pull back on the charging handle with normal force and eject the unfired round, or does it stick in the chamber? These two conditions I think would point to either a bad batch of ammo, or a tight chamber. Try another brand of 5.56 ball and see what happens.

If you keep on having issues, a pre-paid trip back to S&W may be in order.

Larry