The M14 rifle was developed after WWII, and saw service in Korea and Vietnam.  Most were mothballed after the invention of the M16.  In the modern desert wars, there has been a need for a rifle that could engage targets beyond 300 yards (a deliberately designed limitation of the M16).  The US military has added a Squad Designated Marksman (SDM) to many units, and issued him an updated M14.  Several other companies have seen a resurgence in M14 popularity, and have started selling high quality M14-style firearms, parts, and accessories.