Meet the classic M4.
by Kyle Mizokami | The National Interest

The M4 still has its critics, including a retired major general, who have derided this descendant of the M16 as inadequate for modern ground forces. They point to the direct impingement gas operating system, which siphons off hot gases from burning gunpowder to chamber the next round, as guilty of fouling the inside of the rifle, increasing the likelihood of jams.… Read the full article.