Don't want to burst any bubbles here, but the 870's are still in the Marine Corps armories. At least until last month when i last gazed into the hallowed halls.
1st Force Reconnaissance Company has 11 870's, 2 590's and 2 1200's.
The Mossbergs didn't last here, and the 870's are prefered.
Force uses shotguns only for breaching, and while the M1014 is supposed to replace all shotguns in all of the services, it is incapable of firing breaching rounds, so the potential for the 870 remaining at least in small numbers is great.
The M1014- The misnamed Joint Service Combat Shotgun is not a combat shotgun, at least by usage.
The shotgun is primarily a weapon used by guards in certain areas- Ammunition Supply Points, Special Weapons etc.
In I-MEF, which has 45,000 Marines and sailors, 14,397 (appx 33%) are armed with pistols, generally considered to be useless in combat.
The shotgun represents appx 1% (523), and is a T/E rather then a T/O weapon.
The only weapon that was less common was the Sub Caliber Machine Gun. When almost all were dumped in 98, there were 819 throughout the entire Corps.