It appears that the Army still has an adequate supply of M14 rifles.They have been accurizing them at a frantic rate and shipping them out to the troops.
M14s have been used extensively in the Army (see link) since the beginning of current conflicts.
They are also in use by Navy and Marines.
http://www.armytimes.com/news/2010/03/army_m14_032210w/
Over the past 5-6 years I have seen a few articles about the ineffective stopping power of the 5.56mm round. I remember one where troops stated it was taking 2-3 rounds to put down the jihadis. Also remember another where some Special Ops troops were being taught to shoot at lower abdomen rather than center mass to increase chance of stopping their target quickly by hitting a hip or major artery.