INSPECTION — CLEANING — LUBRICATION…
AFTER FIRING YOUR RIFLE, clean it as soon as possible to make the job easier and to avoid allowing the development of any corrosion.
When your firearm has not been fired, you should clean it at least once or twice a year if you live in a temperate climate, or as often as once a week in a tropical climate.
If you get your firearm wet, clean it as soon as possible to avoid the onset of corrosion or rust. Use a high quality rifle cleaning kit that includes a cleaning rod; swab holder; cotton flannel bore patches; pipe cleaners; a small toothbrush; brass wire bristle bore and chamber brushes and a Cleaner/Lubricant/Preservative (CLP in Army terminology).
After you have disassembled the rifle, thoroughly clean, inspect and lubricate all parts according to the techniques described below.
DETAILED CLEANING TECHNIQUES…
NOTE: The procedures below describe cleaning with a standard military issue multi-piece rod cleaning kit. Other commercial cleaning kits may include alternate cleaning instructions which may be just as effective.
CLEANING THE BORE: The bore of your Bushmaster rifle has Lands and Grooves called rifling. Rifling makes the bullet spin very fast as it moves down the Bore and down range. It is difficult to push a new, stiff Bore Brush through the Bore. You will find it much easier, and more effective, to pull your Bore Brush through the Bore. Also, because the brush will clean better if the bristles follow the grooves (this is called tracking), you want the Bore Brush to be allowed to turn as you pull it through.
ALWAYS CLEAN FROM FROM CHAMBER TOWARD THE MUZZLE. Follow these steps:
- Attach three Rod Sections together but leave each one about two turns short of being tight. Attach the Patch Holder but leave it two turns short of tight also.
- Point Muzzle down. Hold the Upper Receiver in one hand while inserting the end of the Rod with Patch Holder attached into the Chamber. Guide the Rod carefully through the Bore. CAUTION: Do not let the Rod or its threaded end scratch the Chrome Lining of the Bore or Firing Chamber. About 2 - 3 inches of the Rod should protrude out of the Muzzle.
- Attach the Handle Section of the Cleaning Rod to the end of the Rod sticking out of the Muzzle, and swab out the Bore with a patch moistened with “CLP”.
- Remove Patch Holder and attach Bore Brush (leaving it two turns short of tight).
- Pull the Brush through the Bore and out the Muzzle. You should be able to see the Rod twisting as you pull it - this is the Brush "tracking" in the rifling.
NEVER reverse the direction of the Bore Brush while it is in the Bore.
- After one pull, take off the handle section and repeat the process. After three or four pulls, the three rod sections and the Bore Brush may become screwed tightly together. Loosen them up and repeat the process.
- Send a patch through the Bore occasionally to help clean out the crud that the brush is getting loose. Just replace the Bore Brush with the Rod Tip (Patch Holder) and a wet patch. Pull it through. If you leave the rods loose again, the patch will "track" in the rifling as before. But remember, always have the Bore wet with cleaner before trying to pull a brush through.
CLEANING THE UPPER RECEIVER…
NOTE: Check to ensure that there is no looseness between the Barrel and the Upper Receiver - if you detect any movement by twisting with your hands, the Barrel Nut must be retorqued. Bring the Rifle to your Armorer.
- Using a “CLP“ type product, clean all areas (inside and out) of Powder Fouling, Corrosion and Dirt.
Never use a wire brush or any type of abrasive to clean the Aluminum Upper Receiver - you'll scratch and damage the finish. A Toothbrush is good for loosening any dirt buildup, and won’t scratch the Receiver.
- Clean the Firing Chamber - dip the larger Chamber Brush in CLP and use at least 5 plunge strokes and 3 - 360° clockwise rotations. Then swab out the Bore as described previously to remove contaminated solution or loosened crud.
- Use the Bore Brush - wet with CLP - to clean carbon and powder residue from around the Gas Tube. Run a Pipe Cleaner into the Gas Tube, clean the Bolt Locking Lugs, Bolt Rings, Firing Pin, Bolt Cam Pin, lip of the Extractor, and inside the Bolt Carrier from both front and rear.
- Wipe all components clean and dry, and inspect for excessive wear, corrosion or mechanical damage. Have your Armorer replace any worn or defective parts before firing again (or contact Bushmaster at 1-800-998-7928 for parts needs.)
Cleaning the Bolt, Bolt Carrier & Components…
- Clean out the Gas Key on top of the Bolt Carrier with a Q-Tip or a Pipe Cleaner. Also clean out an carbon/powder residue from vent holes in the Bolt Carrier.
- Clean and inspect Bolt, Cam Pin, Firing Pin and Firing Pin Retaining Pin thoroughly.
- CHECK THE BOLT: Look for cracks or fractures, especially in the Cam Pin hole area. Inspect Bolt Face - Bolts with any pitting extending into the firing pin hole should be replaced.
- CHECK THE CAM PIN: If it is cracked, or chipped, it should be replaced. NOTE: Cam Pin can only be installed in Bolt from one side - so Ejector will be positioned correctly.
- CHECK THE FIRING PIN: If it is bent, cracked, too blunted or too sharp, it should be replaced.
- CHECK THE FIRING PIN RETAINING PIN: If it is bent, or badly worn, it should be replaced. Never use a “Cotter Pin” as a substitute for a real Firing Pin Retaining Pin. Cotter pins are not made of heat treated spring steel and their round head shape will cause damage.
WARNING: IF THE CAM PIN IS MISSING, DO NOT FIRE THE RIFLE - IT WILL EXPLODE!
Cleaning the Bolt, Bolt Carrier & Components…
- CHECK THE EXTRACTOR AND EXTRACTOR SPRING: If the Extractor is chipped, or has broken edges in the area of the lip that engages the cartridge rim, it should be replaced. Check that the rubber insert is inside the Extractor Spring. Clean off any Carbon buildup or powder residue.
Cleaning / Lubricating the Ejector…
NOTE: The design of the Ejector makes its disassembly for cleaning somewhat impractical (i.e. we don't recommend it). Make sure your Bushmaster ejects empty cases efficiently by following these steps on a monthly basis (more frequently if firing blanks).
- With the Bolt removed from the Bolt Carrier and the Extractor installed, hold it as shown, and dribble a few drops of CLP around the Ejector to form a puddle.
- Take a fired or dummy case and place it under the lip of the Extractor. With a rocking motion, press the case down against the Ejector. Since the Ejector is spring loaded, some resistance will be felt. Press on the case until it stops against the bolt face. Ease off with your thumb slightly and press down again. Repeat several times. Replace the CLP frequently. Once the spring action of the Ejector is smooth and strong, dry off any excess lubricant.
CLEANING THE LOWER RECEIVER…
- Clean all areas of Powder Fouling, Corrosion, Dirt and Rust. Again, never use a wire brush or any type of abrasive to clean the Aluminum Lower Receiver.
- Wipe any dirt from the Trigger Mechanism. Carefully clean the Magazine Release Button and the cavity for the Magazine Catch on the left side of the Receiver. Also inspect and clean the Bolt Catch Mechanism and Receiver’s Takedown and Pivot Pins. Clean the Buffer, Action Spring, and inside the Lower Receiver Extension (the Buffer Tube). A piece of rag attached to the Cleaning Rod and Patch Holder can be used to wipe inside the Buffer Tube.
- If rifle has been used in very dirty/muddy conditions, the Vent Screw in the A2 Solid Buttstock (shown) or the Vent Hole in the Telestock Receiver Extension may need to be cleaned out. Use a Pipe Cleaner or piece if wire to ensure that Vent Hole is clear.
- Buttstocks may require cleaning as necessary. Telescoping Stock Latch can be pulled down to remove Stock. Clean the 6 Position Lock Holes, and lightly lube the Receiver Extension and Latch Mechanism to ensure proper telescoping action. A2 Solid Buttstocks may require cleaning / lubrication of Storage Compartment Door Latch and Hinge, and interior of Storage Compartment.
LUBRICATION – UPPER & LOWER RECEIVERS…
Lightly Lubricate the inside of Upper Receiver, the Bore and Chamber (using the cleaning rod and a patch), the outer surfaces of the Barrel and Front Sight, and surfaces under the Handguards. Be sure you lubricate in and around all the Locking Lugs (as in photo above). The Forward Assist should also be lightly lubed inside the Receiver and checked for function.
Front Sight Detent: Depress and apply two or three drops of CLP to it. Depress the detent severaI times to work the lubricant down into the Spring.
Lower Receiver Extension: Lightly lubricate inside the Lower Receiver Extension (Buffer Tube), the Buffer and the Action Spring. Also lightly lubricate the Telestock Latch and exterior of the Receiver Extension.
Lower Receiver: Generously lubricate ALL MOVING PARTS INSIDE THE LOWER RECEIVER including the Trigger, Hammer, Safety, Bolt Catch, Magazine Release, etc), and their various Pins and Detents. Don't forget the Takedown and Pivot Pins and their Detents. Use an oiled rag to wipe off any fingerprints on the exterior surfaces (they can start the corrosion process). A black cloth is best as it won’t leave visible lint.
LUBRICATION – BOLT CARRIER GROUP…
Firing Pin: Lightly lubricate the Firing Pin with CLP - also the Firing Pin recess in the Bolt.
Bolt: Generously lubricate the Bolt, its Cam Pin area, the Bolt Gas Rings. A lighter application is good on the Extractor and its Pin.
Charging Handle: Lightly lubricate the Charging Handle and its Latch and Spring.
Bolt Carrier: Lightly lubricate the inner and outer surfaces of the Bolt Carrier. Generously lubricate the Cam Pin area and the “Slide” Rail areas of the Bolt Carrier where they contact the inside of the Receiver.
Carrier Key: The inside of the Carrier Key on the Bolt Carrier should be dried with a Q-Tip or Pipe Cleaner - then place one drop of CLP inside.
LUBRICATION – ADJUSTABLE REAR SIGHT…
NOTE: Record how far you move the rear sight so it can be returned to its original position upon the completion of this task.
Rear Sight Moving Parts: Use 1 or 2 drops of CLP. Rotate these parts to ensure that the lubricant is spread evenly above, below and around the threads of the:
- Elevation Knob
- Elevation Screw Shaft
- Windage Knob
- Windage Screw
- Detent Holes
Elevation Screw Shaft: Also lube from inside the Upper Receiver as follows:
- Turn Upper Receiver upside down.
- Remove Charging Handle.
- Put 2 or 3 drops on bottom of Elevation Screw Shaft and in Elevation Detent Spring Hole.
- Rotate the Elevation Dial back and forth a few times while keeping Upper Receiver upside-down.
REASSEMBLING YOUR RIFLE…
- Insert Action Spring and Buffer (the Spring will lock onto the Buffer if you slide it on - then push and twist counterclockwise). Depress Buffer Detent and push Buffer in past the Detent, then release.
- Insert Extractor and Spring.
NOTE: Extractor Assembly has a Rubber Insert within the Spring. Be sure not to lose it. If the Spring comes loose, put the large end of the Spring in the extractor and seat it (a Bullet tip works well).
- Then push down on Extractor to depress Spring, and reinsert Extractor Pin.
- At the back end of the Bolt, stagger the Gas Ring Gaps to reduce gas pressure loss. Position the three ring gaps 120° apart around the bolt (3rd gap not seen at back side of bolt). The rings will slide around in their groove by pushing them into position with a small sharp object.
- Insert Bolt into Bolt Carrier. Twist into position so Cam Pin can be inserted (remember Cam Pin can only be installed in Bolt from one side, so if it doesn’t fit right away, twist the Bolt 180° and try again).
- Once Cam Pin is inserted, twist it 90° (this will allow insertion of the Firing Pin).
WARNING: THE CAM PIN MUST BE INSTALLED IN THE BOLT GROUP. IF IT ISN’T, YOUR RIFLE CAN STILL FIRE AND WILL EXPLODE!
- Drop in and seat Firing Pin. Pull Bolt out, then reinsert Firing Pin Retaining Pin.
NOTE: After inserting Firing Pin Retaining Pin, Firing Pin should not fall out when Bolt Carrier Group is turned upside down.
CAUTION: BUSHMASTER DOES NOT RECOMMEND THE PRACTICE OF SWAPPING BOLTS BETWEEN DIFFERENT RIFLES. DOING SO COULD RESULT IN DAMAGE, PERSONAL INJURY OR DEATH.
- Insert Charging Handle into Upper Receiver and lower the “ears” at front end of Handle into cutouts in Receiver. Then slide Charging Handle partially into Receiver.
- Lower complete Bolt Carrier Assembly into Upper Receiver. Gas Key will fit into groove in the Charging Handle. REMEMBER, Bolt must be pulled to “out” position in the Carrier so Cam Pin will fit into the channel in the Upper Receiver.
- Then slide the Bolt Carrier Assembly and Charging Handle all the way into the Upper Receiver until Charging Handle Latch locks onto the Receiver.
NOTE: If Ejection Port Cover is closed, you will feel some resistance as you push Carrier and Handle in until you pop the Cover open. If Cover is already open, Handle and Carrier should slide in easily.
- To join Upper and Lower Receivers, position Pivot Pin Lug of Upper Receiver into slot at front of Lower Receiver and push Pivot Pin into place.
CAUTION: ALWAYS place the Safety Selector Lever on SAFE before pivoting the Upper Receiver to a closed position on the Lower Receiver.
- After Receivers are closed, push in Takedown Pin.
NOTE: Pivot Pin and Takedown Pin are “captivated” in the Lower Receiver - meaning that they are held in by their Detents and Springs so they cannot fall out and get lost.
HANDGUARD REMOVAL / REATTACHMENT - “THE BUDDY SYSTEM”…
To Remove the Handguards for cleaning, or to Reinstall them, use the “Buddy System”. Because the Slip Ring (often called Delta Ring) which holds the handguards in place has a strong spring (the Weld Spring), it is necessary to have a buddy help you.
CAUTION: THE RIFLE SHOULD BE UNLOADED AND CLEARED.
- Place the Rifle’s Buttstock on the ground or a table, and press down on the Slip Ring with both hands.
- Have your buddy remove or install one Handguard on top and the other on the bottom. There are notches designed to align and hold the Handguards on the Handguard Cap (located just behind the Front Sight Base).
NOTE: The “Half-Round” Handguards are identical and can be used interchangeably in top or bottom positions.
There are also special tools designed to aid in Handguard removal / reinstallation. See Bushmaster’s website (http://www.bushmaster.com) or call 1-800-998-7928
If the Sling, or any other Accessories were removed for cleaning or maintenance, they should be reattached now.
MAGAZINE DISASSEMBLY / REASSEMBLY…
Most Mil. Spec. design M-16 / AR-15 type Magazines can be disassembled for cleaning. The Magazine Spring, Magazine Follower and Magazine Baseplate can be replaced if broken or excessively worn.
- To disassemble Magazine, pry up on bottom of Baseplate using Bullet Tip or Punch, and push indentations in Baseplate past Magazine Body
- Slide Baseplate out of Magazine Body.
- Jiggle Magazine Spring and Follower out of Body.
TO CLEAN and LUBRICATE: Wipe all dirt from the Magazine Body, Spring, Baseplate and Follower. Then lightly lubricate the Spring.
REASSEMBLY is the REVERSE of these steps. Make sure to slide the base under all four tabs until it snaps back under the catch.
NOTE: Do not remove Follower from Spring.