LEARNING OBJECTIVE Describe the operating cycle, safeties, and maintenance of the Remington M870 and the Mossberg M500 shotguns.
Shotguns used by the armed forces are military versions of civilian models procured from military specifications. The Remington model 870 (M870) and the Mossberg model 500 (M500) are the Navy's standard issue riot type of shotguns. In this section we will describe the Remington M870 (fig, 3-50) in detail, then note how the Mossberg 500 differs. The Mossberg 500 is very similar to the Remington 870 in construction and operation.
REMINGTON M870 SHOTGUN
The M870 shotgun, used by the Navy for guard work, is a manually operated magazine-fed (tubular), pump-action shoulder weapon.
The essential features of the Remington M870 shotgun are displayed here in chart form for easy reference.
Functioning of the Remington M870
The M870 shotgun can be loaded and unloaded in several different ways. The following paragraphs describe the different options for loading and unloading the M870 and how to operate the mechanical safety. A single load puts a round directly into the chamber for fast firing, while a magazine load fully loads the tubular magazine, but does not chamber around. Loading the barrel from the magazine chambers a round from the loaded tubular magazine for firing.
SAFETY.- Before loading or unloading, push the safety (fig. 3-5 1) across the rear of the trigger, left to right, to the SAFE position (the red band on the safety will not show).
FIRE POSITION.- Push the safety across to the FIRE position (the red band on the safety will show). The trigger can then be pulled to fire the gun.
SINGLE LOAD.- Push the safety to the SAFE position. Press in the action bar lock (fig. 3-51) if the action is cocked and pull the fore-end fully to the rear. Place the shell into the open ejection port upon the downthrust carrier. Slide the fore-end toward the muzzle to load the shell into the barrel chamber and leek the action closed
MAGAZINE LOAD.- Push the safety to the SAFE position. Slide the fore-end completely forward to close the action. Turn the gun bottom upward and press the shell against the carrier, then forward fully into the magazine. Make sure the rim of the shell snaps past the shell latch to prevent the shell from sliding back over the carrier. Should this occur, open the action or, if necessary, remove the trigger plate assembly (fig. 3-52) if the gun is cocked to remove the shell.
LOADING THE BARREL FROM THE MAGAZINE.- Shells can be fed from the loaded magazine by simply pumping the fore-end. Press in the
Figure 3-51.-Remington M870 receiver nomenclature.
Figure 3-52.-M87O trigger plate assembly.
action bar leek if the gun is cocked Pump the fore-end back and forth to open and close the action.
UNLOADING THE GUN.- Pushthe safety to the SAFE position. Press in the action bar lock; pull the fore-end (fig. 3-53) slowly rearward until the front end of the shell from the barrel is even with the ejection port in the receiver. Lift the front of the shell outward and remove it from the ejection port. Continue pulling the fore-end back fully until the next shell releases from the magazine. Roll the gun sideways to allow the released shell to drop from the ejection port. Close the action by
pushing forward on the fore-end. Continue this same method until the magazine and gun are empty.
Open the action and check the shell chamber in the breech and magazine to make sure no rounds remain in the gun.
UNLOADING THE BARREL ONLY.- Push the safety to the SAFE position. Press in the action bar leek and pull the fore-end rearward until the front end of the shell from the barrel is even with the front end of the ejection port. Lift the front end of the shell from the receiver as described previously. A shell with different powder and shot combination may then be placed in the chamber and the action closed without disturbing shells in the magazine.
Figure 3-53.-M87O fore-end assembly.