Bringing the Military use of the shotgun up to date, this months American Rifleman (May)has a very through article by Bruce Canfield.

As a side note, the 870 continues to be widely used in the Special Operations world. Most commonly has a 10" barreled, 3 +1, pistol grip only breacher. 3+1 is sort of a misnomer since they are typicaly not carried with a round in the chamber. That honor is saved for the M-4 carbine or MK-18 and soon the SCAR.

DMR