Mossberg MMR User Manual
OWNER’S
MANUAL
MMR
MOSSBERG
MODERN RIFLE
SEMI-AUTOMATIC RIFLE
WITH DETACHABLE MAGAZINE
IMPORTANT “SAFETY WARNINGS” — NOTE THE SYMBOL
THESE SAFETY WARNINGS ARE FOR YOUR PROTECTION AS WELL
AS THE SAFETY OF OTHERS. DISREGARDING INFORMATION IN THIS
MANUAL MAY RESULT IN SERIOUS INJURY OR DEATH.
Be certain this owner’s manual is available for reference and is kept with
this rearm if transferred to another party. If this manual is lost or misplaced,
contact the Product Service Center for a free replacement copy.
After performing any work on your rearm such as cleaning, adjustments,
disassembly or installation of any accessory, the rearm should be
re-checked for proper functioning before ring live ammunition.
Firearms are complex mechanisms. Any modication, alteration, or improper
tting of parts may result in a dangerous malfunction, damage to the rearm,
and injury to the shooter and/or others nearby. The rearm’s owner must
accept full responsibility for the correct reassembly and functioning of the
rearm after any disassembly or replacement of parts.
TM
If you do not understand any of the material in this manual or have any
questions, contact the Product Service Center or a qualied gunsmith.
Do not attempt to load, handle or use the rearm until you read and
understand the information contained in its owner’s manual. Before handling
your rearm, you should learn how it operates and how to maintain it. This
includes knowing its basic parts, how the manual safety and other safety
features operate, how to safely open and close the action and how to safely
load and unload ammunition from the rearm. Improper use and handling is
dangerous and could cause serious injury or death to you or those around
you. All users of the rearm must become thoroughly familiar with the
instructions in this manual.
O.F. MOSSBERG & SONS, INC.
P.O. BOX 497 • 7 GRASSO AVENUE, NORTH HAVEN, CT 06473
PHONE (800) 363-3555
www.mossberg.com
Safety and safe firearms handling is everyone’s responsibility.
2
As the owner of a rearm, you must undertake the full-time responsibility
of safe rearms handling for your own safety and the safety of those
around you:
• Keep all rearms and ammunition out of the reach of children.
• Store your rearms and ammunition separately.
• Never store a loaded rearm.
• Never leave a loaded rearm unattended.
• Never transport a loaded rearm in a vehicle.
• Unload your rearm when you have stopped shooting and when
you have to climb a tree, fence, cross a slippery surface or have to
transport it in a vehicle.
• Do not load your rearm before you are in a place where it is safe
to shoot, and keep your nger off the trigger until you are on target
and have decided to re.
• Never shoot at water, rocks or any hard surfaces. Bullets may
glance off such surfaces and cause injuries.
• Do not use alcohol or drugs before or while handling rearms.
• Do not touch the trigger while the safety selector lever is being
engaged or disengaged.
Always point the muzzle of your rearm in a safe direction, regardless of
whether the rearm is loaded or unloaded. You should become thoroughly
familiar with the function and operation of this rearm and the instructions
supplied with it.
Always treat every rearm as if it is loaded. Give your rearm to someone
with the action open (bolt fully rearward), and the safety selector lever fully to
the “ON” (SAFE) position, after you verify the rearm is unloaded. Insist on
the same procedure when receiving a rearm from someone else. Learn the
location of all the safety features of your rearm and how they operate.
Wear eye and ear protection when shooting. Shooting without proper ear
protection can cause hearing damage. The use of eye protection during any
type of shooting is important to protect your vision.
When using a rearm with mounted optics, maintain an adequate distance
between the rear of the scope and your face at all times. Be certain the scope
installation does not interfere with access to, or the proper functioning of the
safety selector lever.
We specically disclaim any responsibility for damage or injury
whatsoever occurring in connection with, or as a result of, the use
of faulty, or non-commercially manufactured, or remanufactured or
hand-loaded (reloaded) ammunition. Additionally, we disclaim any
responsibility for damage or injury which results from any modications
or changes that are not a part of the rearm as delivered from the factory.
Learn to clean your rearm thoroughly and make certain no oil, grease or
other materials are blocking the barrel. Obstructions of any kind can cause
damage to the rearm resulting in personal injury.
Practice proper rearm maintenance and safety. Make sure all exposed metal
surfaces are coated with a thin lm of oil, especially after being exposed to damp
weather. (See the proper section of this manual for cleaning instructions.) Do not
plug the barrel or store in a fabric-lined case, which will absorb lubricants from
the rearm. Before using after storage, follow complete instructions stated in this
manual for re-familiarization with the rearm. A thorough inspection and function
test should be performed before going into the eld. Have your rearm periodically
checked by a qualied gunsmith.
PART NO. 19818 REV. A
2
A note about the warnings and information contained in this manual:
We strongly suggest that you check with your local licensed retailer or state
police for additional information concerning rearms ownership, or hunting
or target shooting rules that may be required by local law or regulation.
Since such rules and regulations are subject to change, local authorities are
in the best position to advise you on such matters.
TABLE OF CONTENTS
Page
General Information and Mechanical Characteristics . . . . . . . . . . . . . . . . . . . 4-6
Mechanical Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Opening the Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Removing the Magazine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Loading the Firearm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9
A. Loading the Magazine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
B. Loading the Magazine into the Firearm . . . . . . . . . . . . . . . . . . . . . . . .. . . 8-9
C. Unloading the Firearm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
D. Unloading the Magazine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Firing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-15
Cleaning and Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-17
Assembly and Final Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-19
Function Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-20
Sight Adjustments (Tactical Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21
Adjustable Buttstock (Tactical Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Service Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Parts List For Hunter Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Exploded View For Hunter Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Parts List For Tactical Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Exploded View For Tactical Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-31
Basic Rules of Safe Firearms Handling . . . . . . . . . . . . . . . . . . . . . . Back Cover
3
GENERAL INFORMATION AND MECHANICAL CHARACTERISTICS
The MMR
TM
is designed to operate with the ammunition caliber inscribed on the
barrel and as shown below:
5.56mm NATO can also re .223 Rem rie cartridges
7.62mm NATO can also re .308 Win rie cartridges
When the rearm leaves the factory, its metal parts are protected by a coat of
very adherent oil. This coating, especially inside of the barrel, must be removed
before using the rearm. The oil on the outside surfaces should also be removed
when the packing box has been opened because the oil is very sticky and it easily
retains dust and other solid impurities from the air.
WARNING
Because this rearm can be used as a single shot, it will re whether or
not a magazine is in the rearm if a cartridge is chambered.
FIREARM WILL FIRE WITH MAGAZINE OUT.
Be sure the cam pin is installed in the bolt carrier assembly. The rearm will
re without the cam pin and the rearm will explode, causing damage to
your rearm and may result in serious personal injury to the shooter and/
or others nearby.
Check your rearm for proper functioning before loading or ring live
ammunition.
This rearm could chamber a cartridge if dropped or jarred with a loaded
magazine in place and the bolt carrier assembly locked to the rear or in its
forward position.
When ring a large number of cartridges in a short period of time, the barrel
of the rearm will become extremely hot. If this rearm stops ring with
a live cartridge in the chamber of a very hot barrel, remove the magazine
and chambered cartridge immediately and allow the rearm to cool. This
rearm could re just from the heat of the barrel.
The MMR
TM
is designed to re semi-automatically. A single cartridge will re
each time the trigger is pulled. Finger pressure must be relieved from the trigger
before an additional shot can be red.
The MMR
magazines of various capacities will function in the 5.56mm NATO MMR
Mossberg factory magazines or aftermarket magazines of the same style in the
7.62mm NATO MMR
TM
handguards are free oat tubes. Standard AR-15 / M16 type
TM
.
4
TM
. Use
GENERAL INFORMATION AND MECHANICAL CHARACTERISTICS CONT.
SHELL DEFLECTOR
EJECTION PORT
UPPER RECEIVER
TAKEDOWN PIN
LOWER RECEIVER MAGAZINE RELEASE BUTTON
PICATINNY RAIL
FRONT SWIVEL STUD
PIVOT PIN
MAGAZINE WELL
Fig. 1 – MMR 5.56 Hunter (Right Side)
BOLT CATCH CHARGING HANDLE
SAFETY
SELECTOR
LEVER
TRIGGER PISTOL GRIP
REAR SLING MOUNT
HANDGUARD
MUZZLE
BUTTSTOCK
Fig. 2 – MMR 5.56 Hunter (Left Side)
Fig. 3 – MMR 5.56 Tactical w/ optional sights (Right Side)
Fig. 4 – MMR 5.56 Tactical w/ optional sights (Left Side)
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GENERAL INFORMATION AND MECHANICAL CHARACTERISTICS CONT.
Fig. 5 – MMR 7.62 Hunter (Right Side)
Fig. 6 – MMR 7.62 Hunter (Left Side)
MECHANICAL SAFETY
The safety selector lever is located on the left side of the receiver above the
trigger and must be manually rotated to the desired position by the shooter.
Remember, a rearm’s manual safety is a mechanical device which can
never replace safe rearm handling practices.
Never rely on any mechanical mechanism or safety device to prevent the
dangers of careless handling or pointing a rearm in an unsafe direction.
To put the manual safety in the “ON” (SAFE) position, the safety selector
lever must be rotated fully to the horizontal position (Fig. 7). The safety
selector lever will now point toward the “SAFE” stamping on the receiver. The
stamp is a training aid used only to show the direction of the “ON” (SAFE) position
and should not be used as an indicator that the manual safety is “ON” or “OFF.”
Rotating the safety selector lever fully to the vertical position will put the manual
safety in the “OFF” (FIRE) position (Fig. 8). The safety does not rotate to the “ON”
(SAFE) position if the rearm is not cocked.
SAFETY ON (SAFE)
Fig. 7 Fig. 8
SAFETY OFF (FIRE)
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OPENING THE ACTION
The bolt catch is located on the left side of the receiver above the magazine well
(Fig. 2).
The bolt catch allows the action to be held open for inspection of the chamber
and action or unloading without pulling the trigger. The action may be manually
opened by pulling the charging handle out and pressing on the bottom of the bolt
catch until the action catches and stays open (Fig. 9).
Note: The action will lock open when an empty magazine is installed, and the
action is cycled by pulling the charging handle rearward.
Fig. 9
REMOVING THE MAGAZINE
WARNING
Because this rearm can be used as a single shot, it will re whether or
not a magazine is in the rearm if a cartridge is chambered.
FIREARM WILL FIRE WITH MAGAZINE OUT.
Removal of the magazine will not unload the rearm! After you remove the
magazine always visually and physically inspect the chamber and receiver
to ensure the rearm is completely unloaded!
This rearm is equipped with a removable magazine. The magazine can be
removed with the action in the open or closed position. Remove the magazine by
pressing on the magazine release button (Fig. 10). Most magazines will fall freely
from their seat. Familiarize yourself with the rearm by installing and removing
an unloaded magazine and by learning to keep the action in the open position.
Fig. 10
7
LOADING THE FIREARM
Before loading, rotate the safety selector lever fully to the horizontal
position to place it in the “ON” (SAFE) position.
Before loading, visually and physically inspect the chamber and bore of the
barrel for any obstruction, excessive oil or grease. (The chamber is the rear
portion of the barrel which will contain the cartridge.) Obstructions of any
kind can cause damage to the rearm and may result in serious personal
injury to the shooter and/or others nearby.
During loading never allow ngers or any objects to contact the trigger.
Keep the muzzle pointed in a safe direction at all times.
Do not load rearm until ready for use! Unload rearm when shooting has
been completed! The safety selector lever should always be in the “ON”
(SAFE) position whether the rearm is loaded or not.
Check to be certain that the correct ammunition has been selected for use.
Ensure it is the same caliber and type of cartridge as designated on the left
side of the barrel.
This rearm is capable of ring a chambered cartridge with the magazine
empty, without the magazine inserted, or if the magazine is dislodged from
its seat.
A. LOADING THE MAGAZINE
To load the magazine, remove the magazine by pressing the magazine release
button. Hold the magazine in one hand and insert one cartridge at a time (Fig. 11),
pressing against the magazine follower and rearwards until the magazine is full, or
until the desired number of cartridges has been loaded.
Fig. 11
B. LOADING THE MAGAZINE INTO THE FIREARM
Insert a loaded magazine into the rearm by sliding the magazine up into the
magazine well until it is retained by the magazine catch (Fig. 12). Pull on the
magazine to make sure the magazine is rmly seated (Fig. 13). Press the upper
portion of the bolt catch to close the action and load a cartridge into the chamber
(Fig. 14).
The rearm is ready for ring as soon as the safety selector lever is
rotated fully to the “OFF” (FIRE) position.
8
Fig. 12 Fig. 13
Fig. 14
To minimize the risk of unintended ring, leave the chamber empty and the
safety selector lever in the “ON” (SAFE) position until you are on target and
have decided to re. Keep the muzzle pointed in a safe direction at all times
and your ngers and any other objects away from the trigger.
C. UNLOADING THE FIREARM
Rotate the safety selector lever fully to the “ON” (SAFE) position. During
unloading, never allow ngers or any other object to contact the trigger.
KEEP THE MUZZLE POINTED IN A SAFE DIRECTION AT ALL TIMES.
Remove the magazine by pressing the magazine release button. Pull the charging
handle back while pressing on the lower portion of the bolt catch until the action
catches and stays open. This will extract a loaded cartridge from the chamber.
After unloading always visually and physically inspect the chamber, receiver
and magazine to make sure that all of the cartridges have been removed.
D. UNLOADING THE MAGAZINE
Hold the magazine in one hand bottom down and front end forward. Push the
cartridge forward and allow the nose of the cartridge to rise slightly upward until it
is released from the magazine. Repeat until magazine is unloaded.
FIRING
Discharging rearms in poorly ventilated areas, cleaning rearms, or
handling ammunition may result in exposure to lead and/or other
substances known to cause birth defects, reproductive harm, and/or other
serious physical injury. Have adequate ventilation at all times. Wash hands
thoroughly after exposure.
9
With the rearm pointed in a safe direction and held in the proper ring position,
rotate the safety selector lever fully to the vertical “OFF” (FIRE) position (Fig. 15).
Pulling the trigger through its full travel to the rear will re the rearm.
After the rearm is red the action will be cycled by the gas system and automatically
load the next cartridge. The trigger must be fully released before the rearm will be
ready to re again.
Fig. 15
If there is a pause in ring, rotate the safety selector lever fully to the “ON” (SAFE)
position. If so equipped, the ejection port cover will automatically open when the
rearm is red again or when the bolt is manually opened (Fig. 16).
EJECTION PORT COVER CLOSED
Fig. 16
Should a cartridge fail to re after pulling the trigger, keep the rearm pointed
in a safe direction in case of a hangre. Wait a few moments then pull the
charging handle to the rear to extract and eject the misred cartridge and
segregate from other ammunition. Do not attempt to rere a misred cartridge.
If at any time during ring, the sound of any given cartridge is noticeably
louder or softer than previous cartridges red, STOP! Do not load or
re additional cartridges until you have safely unloaded your rearm and
inspected it for possible damage or obstruction in the chamber or bore.
(The bore is the inside surface of the barrel.) Firing the rearm with a
bore obstruction can cause damage to the rearm and may result in serious
personal injury to the shooter and/or others nearby.
When ring a large number of cartridges in a short period of time, the barrel
of the rearm will become extremely hot. If this rearm stops ring with a
live cartridge in the chamber of a very hot barrel, remove the magazine and
chambered cartridge immediately and allow the rearm to cool. This rearm
could re just from the heat of the barrel.
10
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