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User Manual and Cleaning Procedures

Overview

Follow these procedures for maintenance, use and care of your rifle.

INTRODUCTION

  • GENERAL INFORMATION: This Manual includes specific operating and maintenance instructions, and safety information pertaining to all Bushmaster BA50 .50 BMG (Browning Machine Gun) Caliber Bolt Action Rifles and Carbines.
  • PREPARATION FOR STORAGE OR SHIPMENT: Except in extreme situations, Bushmaster BA50 models should always be stored and transported in their original factory cases.

SPECIFICATIONS

  • CALIBER: .50 BMG (Browning Machine Gun Cartridge) [12.7 X 99 mm]
  • WEIGHT: Rifle: 30 Lbs. [13.61 kg] / Carbine: 27 Lbs. [12.25 kg]
  • OVERALL LENGTH (Assembled): Rifle: 58” [147.32 cm] / Carbine: 50” [127.00 cm]
  • BARREL LENGTH: Rifle: 30” [76.2 cm] / Carbine: 22” [55.88 cm]
  • RIFLING: 1 x 15” [38.1 cm]
  • MAGAZINE CAPACITY: 10 Rounds
  • BUTTSTOCK: Standard AR15 Type with Trapdoor Storage Compartment
  • SAFETY: Standard AR15 Type Safety with Manual Thumb Lever - Left Side
  • OPTIC MOUNTING RAIL: MIL-STD 1913 Rail
  • MUZZLE VELOCITY: Approximately 2850 fps [853 mps] w. std. 660 grain [42.8g] projectile
  • MAXIMUM RANGE: Approximately 22,300 ft. [6,800 meters]

MAINTENANCE

Inspection of Rifle's Major Groups:

The Rifle's Four Major Groups are:

  • LOWER RECEIVER
  • BOLT CARRIER GROUP
  • UPPER RECEIVER/BARREL ASSEMBLY
  • BIPOD ASSEMBLY

Ensure all components are present, and inspect for obvious damage. Report any discrepancies or problems to Bushmaster Customer Service (1-800-883-6229). Detailed
inspection should be conducted as described below.

50 bmg.PNG

Inspection of the Lower Receiver:

  1. Lower Receiver should not have any pits or cracks, the Butt Stock and Pistol Grip should not move and must be firmly attached to the Receiver. All the Trigger Group Parts should be functioning properly. Both the Take Down Pins should be in the Receiver.

Inspection of the Bolt Carrier Group:

  1. The Bolt should move freely in and out of the Bolt Carrier by rotating with the Cam Pin.
  2. The Ejector and Extractor must be checked to ensure they are under spring tension and show no signs of chipping ,cracking or wear.
  3. The Carrier Pin which holds the Firing Pin in place should not be bent or cracked, and the Spring/Detent mechanism at its tip should be functional in order to hold the pin within the Bolt Carrier.
  4. Inspect Firing Pin Protrusion by pushing the Bolt into the Carrier and manually pushing the Firing Pin forward. Check the Firing Pin hole on the Bolt Face. Make sure it is not eroded or elongated. Bolt face should not be pitted.
  5. The Carrier Bearings should not be tightly screwed into the Carrier on the top side. You should not disassemble these parts unless you need to remove the Firing Pin Sleeve, Sleeve Set Crew and Firing Pin- then only the Rear Roller Bearing needs to be unscrewed. The Firing Pin Sleeve Set Screw is underneath the Rear Roller Bearing Cap Screw. (See Bolt Carrier Group)

Inspection of the Upper Receiver:

  1. The Barrel should be clean and free of any obstructions.
  2. The Hand Guard should be tightly attached to the Barrel Locking Collar. Do not remove the Hand Guard.
  3. The Bipod Assembly Mount should be attached to the Hand Guard tightly. Do not remove this Mount.
  4. The Upper Receiver body should not be cracked, chipped, pitted or worn.
  5. Muzzle Brake should not be tightly screwed to the barrel. Do not remove or disassemble the muzzle brake! This rifle should never be fired without its muzzle brake.
  6. All Scope Mountings should be tight, in good condition, and free of oil.

Inspection of the Bipod:

  1. If any parts of the Bipod are cracked, do not use it. Replace it immediately.
  2. The Bipod Legs should not be bent.
  3. All parts of the Bipod should be clean and dirt free to function properly.

CAUTION: BEFORE BEGINNING ANY RIFLE CLEANING PROCEDURES, MAKE SURE THE RIFLE IS UNLOADED BY VISUALLY CHECKING THAT THE FIRING CHAMBER IS EMPTY AND THE MAGAZINE HAS BEEN REMOVED FROM THE LOWER RECEIVER.

General Maintenance:

  1. Ensure that all bearing surfaces and exposed parts – particularly those listed below – are clean and properly lubricated.
        BOLT AND CARRIER
        TRIGGER ASSEMBLY
        BIPOD ASSEMBLY
  2. Inspect all parts and tighten or replace as necessary. Each time the rifle is assembled for firing, make sure the barrel and chamber are free of excess oil. If possible, perform an operational check with dummy rounds (up to 10 – maximum magazine capacity) to confirm proper function. This insures that ammunition will chamber and extract properly.
  3. Before Firing the Rifle: Thoroughly clean and dry the Bore and Chamber. Use cleaning rods by inserting them from the Chamber to the end of the barrel. Be careful not to damage the Muzzle Crown since this effects the accuracy of the Rifle.
  4. After Firing the Rifle: The Rifle should be cleaned and lubricated as soon as possible after each shooting session. After every 50 rounds it is recommended that the Chamber and Bore be scrubbed with a copper solvent to remove deposits.
  5. Long Term Maintenance: If the Rifle is not being fired for 30 days or more, oil the Rifle –especially the Bore and Chamber – depending on climate conditions in your area. For storage periods of six months or more, apply a good quality coating oil to the Rifle and inspect it for re-oiling every six months.
  6. Troubleshooting: If you experience any difficulty pulling back on the Bolt Handle, you may have a dirty Chamber that needs cleaning, or the ammunition you are using has too much chamber pressure – and should not be used. If you have difficulty closing the Bolt during firing you may have an obstruction in the Chamber requiring cleaning, or your ammunition might be out of specification – and should not be used.

ASSEMBLY & DISASSEMBLY PROCEDURES

caution.PNG WARNING: THE MUZZLE BRAKE ON THIS RIFLE SHOULD NEVER BE REMOVED OR DISASSEMBLED. SERIOUS INJURY CAN OCCUR IF RIFLE IS FIRED WITHOUT A MUZZLE BRAKE.

Assembly of Major Parts of the Rifle:

The Rifle is shipped in either a Cardboard Case with Foam Inserts or an optional Hard Plastic Shipping Case. It is shipped disassembled in the case-comprised of four groups:

Upper Receiver & Barrel Assembly/Lower Receiver Assembly/ Bipod/ Magazine

Take the Upper Receiver out of the Case by holding onto the Muzzle Brake and the Receiver Housing (don’t let the Bolt Carrier Group fall out of the Upper Receiver). Place it on a table or flat surface. Insert the Bolt Handle with Bolt Handle Sleeve into the Bolt Carrier Group and tighten the Bolt Handle Set Screw with supplied Allen Wrench. Pull the Bolt Handle back.
Inspect the Chamber to make sure it is empty and clear.

Safety Mechanism:

There is a single Thumb-Lever which prohibits the Rifle from firing by blocking the rear of the Trigger from rotating up, effectively preventing the Hammer from being released under spring tension. The BA50 also has a Firing Pin Safety that does not allow the Firing Pin to protrude out of the Bolt unless the Bolt is rotated and locked.

Now take the Lower Receiver out of the Case and manually push the Hammer back until it is cocked. Turn the Safety Selector Lever to SAFE (horizontal position, see Figure 1 ). The pointed end of the Safety Selector Lever should point towards the SAFE marking.

Assembling the Rifle...Upper Receiver to Lower

Push the Front Pivot Pin and the Rear Take Down Pin out of the Lower Receiver from the left side. Assemble the Upper Receiver with the Lower by aligning the Pivot Pin hole first. Push the Pivot Pin into the Upper Receiver from right to left.

With the Hammer cocked, and the Safety Selector on SAFE, pivot the Upper Receiver down onto the Lower Receiver. When Receivers are completely closed, the Rear Take Down Pin can be pushed in from right to left to complete this assembly.

Note: Front Pivot Pin and the Rear Take Down Pin are “captivated” by their detents so they can’t fall out and be lost.

50 bmg assembly.PNG

Assembling the Rifle...Bipod Assembly

Remove the Bipod Attachment Nut by unscrewing it from its stud on the Handguard (may require a 3/4” wrench to initially loosen it). Attach the Bipod onto the Upper Receiver by sliding
it onto the Bipod Stud, then screw the Bipod Nut back on. Tighten by hand, then with 3/4” wrench.

caution.PNG

CAUTION: RIFLE IS NOW READY FOR USE. DO NOT INSERT A LOADED MAGAZINE UNTIL YOU ARE AT A SHOOTING RANGE AND READY TO FIRE THE RIFLE. ALWAYS REMEMBER TO USE EYE AND EAR PROTECTION.

AMMUNITION

caution.PNG

CAUTION: USE ONLY HIGH QUALITY, CLEAN, DRY AMMUNITION FROM A REPUTABLE MANUFACTURER. FAILURE TO DO SO MAY PLACE YOU, OR THOSE AROUND YOU AT RISK, AND MAY DAMAGE YOUR RIFLE, AND/OR VOID YOUR WARRANTY.

If you buy ammunition that is over-pressured, or is possibly old or surplus, firing such ammunition will cause the brass to swell and stick in the Firing Chamber, and cause problems when pulling back on the Bolt Handle for Case extraction. Only new, high quality ammunition from reliable manufacturers should be fired in this rifle.

Firing the Rifle

Break-in Period...

NOTE: YOUR MODEL BA50 RIFLE WILL REQUIRE SHOOTING ABOUT 75 ROUNDS TO BREAK IN PROPERLY.  The Bolt Action of the Rifle will get smoother after the break in period.

Every time you pull the Bolt Handle back to charge a new round, pull the Handle back all the way, and push it forward and down all the way. If the Bolt is not properly closed, you should not fire the Rifle. To visually check if the Bolt is closed properly, look at the Ejection Port Opening. The Bolt Carrier should be flush with the Barrel Extension. If it is not, the Bolt is not completely closed. The Bolt Handle should be all the way down in the Handle Slot in the Upper Receiver. Eject the round and inspect the Chamber for any obstruction. The Firing Chamber may need cleaning if the Rifle has fired more than 50 Rounds.

 

When you are ready to fire the Rifle, make sure you have a safe place to shoot – with a good back stop sufficient to stop a .50 BMG round. Keep the Rifle pointed down range. Unlock the Bolt and pull it back all the way. Place the Rifle’s Safety on SAFE position.

 

Insert a loaded Magazine while pushing the Magazine Release Button in about 1/8th of an inch. Once the Magazine is inserted about 1 inch into the Magazine Well, release the Magazine Release Button. PUSH up on the bottom of the Magazine to make sure it is properly inserted into the Magazine Well.

 

When you are ready to fire, push the Bolt Handle forward and then down. The Bolt will push a round from the Magazine into the Firing Chamber. Make sure the Bolt Handle is down all the way. Look at your target through your scope or sights, acquire the target, move the Safety Selector to the OFF position, aim, and pull the Trigger. The Trigger has a 4 to 6 lb. pull. Do not tamper with the Trigger system - this will void your Warranty. After you have fired the round, pull the Bolt Handle up and back, the Bolt will eject the fired round. Then move the Safety Selector to the SAFE position before you observe your target with a spotting scope. To reload another round, simply repeat the same procedure. To remove the Magazine, push the Magazine Release Button and pull the Magazine out of the Lower Receiver.

RIFLE DISASSEMBLY PROCEDURES

DISASSEMBLY OF THE RIFLE FOR STORAGE OR CLEANING...

caution.PNG CAUTION: BEFORE BEGINNING ANY RIFLE CLEANING OR DISASSEMBLY PROCEDURES, MAKE SURE THE RIFLE IS UNLOADED BY VISUALLY CHECKING THAT THE FIRING CHAMBER IS EMPTY, AND THE MAGAZINE HAS BEEN REMOVED FROM THE LOWER RECEIVER.

Disassembly will be the reverse of some of the procedures already described for Assembly. Push out the Rear Take Down Pin from the left side, pivot the Upper Receiver to an open position, and push the Front Pivot Pin out to separate the Upper and Lower Receivers. Place the Upper Receiver on a flat solid surface.

Removing the Bolt Carrier Group

Refer to figures 2 & 3

 

Pull the Bolt Handle up and slide it back to expose the Firing Chamber. Check again to make sure the Chamber is empty and the Rifle is unloaded. Now close the Bolt, and rotate the Bolt Handle down. You will see a Set Screw on the Bolt where the Handle is attached to the Bolt.

 

Using the 3/32” Allen Wrench provided, unscrew the Set Screw until it is rotated out of the Bolt about 1/8th inch. Once the Set Screw is loose, unlock the Bolt by lifting Handle up, then slide the Handle out of the Bolt along with the Handle Sleeve. Then slide the Bolt Carrier Group out of the rear of the Upper Receiver.

50 bmg disassembly fig 2.PNG

50 bmg disassembly fig 3.PNG

Bolt Carrier Disassembly-Removing Clevis Pin

After sliding the Bolt Carrier out of the Upper Receiver, remove the Carrier Pin (which holds the Firing Pin within the Carrier) by pushing in it’s detent (on the right side of the Carrier - Figure 4 below). Then remove the Carrier Pin by pulling it out of the Bolt Carrier.

50 bmg disassembly fig 4.PNG

Firing Pin/Cam Pin/Bolt Removal

The Firing Pin Sleeve, Firing Pin and Firing Pin Spring can be removed by unscrewing the Rear Roller Bearing Cap Screw and the Firing Pin Sleeve Set Screw underneath it in the Carrier (”A” - Figure 7 below). Then slide the Firing Pin Sleeve, Firing Pin and Firing Pin Spring out of the rear of the Bolt Carrier (“B” below).

 

Once the Firing Pin Sleeve, Firing Pin and Spring have been removed, the Cam Pin (”C” below) can be pulled up and out. Then the Bolt can be pulled out of the front of the Carrier.

50 bmg disassembly fig 6.PNG

50 bmg disassembly fig 7.PNG

Bolt Carrier Group

Shown here are the disassembled components of the Bolt Carrier Group.

50 bmg bolt carrier group.PNG

stop.PNG

 

BUSHMASTER DOES NOT RECOMMEND ANY FURTHER DISASSEMBLY. DOING SO WILL VOID YOUR WARRANTY.

 

CLEANING

AFTER FIRING YOUR RIFLE, clean it as soon as possible to make the job easier and to avoid allowing the development of any corrosion due to powder residue. Even when your Rifle 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 YOUR RIFLE GETS WET, clean it as soon as possible to prevent 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 appropriate to the .50 BMG Caliber of this Rifle, and a Cleaner/Lubricant/Preservative (CLP).

CLEANING THE BORE: The bore of your Bushmaster rifle has Lands and Grooves called Rifling. Rifling makes the bullet spin 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 (called tracking), you want the Bore Brush to be able to turn as you pull it through.

ALWAYS CLEAN FROM FROM CHAMBER TOWARD THE MUZZLE. Commercial rifle cleaning kits may include alternate cleaning instructions which may be just as effective.

  1. Insert the Cleaning Rod into the muzzle end of the barrel. Rod should be long enough so it will protrude from the end of the Upper Receiver and allow you to easily insert Cotton Cleaning Patches into the Patch Holder attachment of the Rod. Cleaning Patch should be moistened with “CLP” or other suitable bore cleaner.
  2. Pull the Cleaning Rod out from Receiver towards Muzzle.
  3. Remove the Patch Holder from Rod, reinsert rod through barrel from Muzzle end, and attach the .50 BMG size Bore Brush (Bore diameter of this Rifle is .510 inches).
  4. Pull the Brush through the Bore and out the Muzzle. The Rod should be able to twist as you pull it - allowing the Brush to "track” in the rifling.

NEVER reverse the direction of the Bore Brush while it is in the Bore. Always pull Brush or Patch from Receiver towards Muzzle (following the path of the bullet to ensure that any fouling or powder residue is removed).

  1. After the first pull with the Bore Brush, remove Brush from Rod – reinsert Rod in Muzzle – reattach Brush. Repeat this process for three or four pulls.
  2. Send a patch through the Bore occasionally to help clean out the fouling that the brush is getting loose. Just replace the Bore Brush with the Patch Holder, a wet patch, and pull it through. Remember to always have the Bore wet with cleaner before trying to pull a brush through. Bore cleaning is complete when bore appears bright and shiny, and a final Patch comes through clean.

CLEANING OTHER COMPONENTS OF THE RIFLE...

BOLT CARRIER GROUP:

The parts of the Bolt Carrier Group should be wiped down with CLP type Cleaner (or other suitable solvent), and lightly oiled with a quality gun oil before reassembly.

UPPER RECEIVER/BARREL ASSEMBLY & LOWER RECEIVER:

The interior and exterior of the Upper Receiver/Barrel Assembly and the Lower Receiver should be thoroughly cleaned with CLP type Cleaner (or other suitable solvent). Lightly oil all surfaces before reassembly. Pay particular attention to lubrication of the Hammer, Trigger and Safety Selector, and test for smooth function before reassembly.

BIPOD ASSEMBLY:

Clean with CLP solvent and a small brush (toothbrush) to remove any exterior dirt or mud.

Lubricate all moving parts with quality gun oil.

MAGAZINE:

The Magazine can be disassembled by sliding the Base Plate off the Magazine Body after prying up the front end of the plate (use an Allen Wrench or Screwdriver for leverage). The Magazine Spring can then be worked-side to side-out of the Magazine Box. Then the Cartridge Follower can be dropped out of the Magazine Box.

Clean all parts, and lightly lubricate before reassembling in reverse order from description above. Note that the Follower will only fit into the Magazine Box one way, and the Spring must be oriented so as to fit over the heavy protrusion on the underside of the Follower.

50 bmg magazine.PNG

 

ASSEMBLY AFTER CLEANING

Assembly of the Bolt Carrier Group

Insert the Bolt into the Bolt Carrier – the large lug on the Bolt with the hole for the Bolt Handle should be facing up (refer to Figures 6, 7 & 8 above for assistance) You’ll be able to see the Cam Pin hole through the large slot at the top of the Bolt Carrier. Insert the Cam Pin with its hole for the Firing Pin aligned so that you can slide the Firing Pin and Firing Pin Spring into the back of the Bolt. The Firing Pin should be inserted – with its protruding side pins in a horizontal position – through the Cam Pin to hold the Cam Pin in place. Then rotate the Bolt so the Cam Pin moves in its slot down the side of the Carrier, and when you can see through the Carrier Pin holes in the Bolt Carrier and the Bolt, you have proper alignment to insert the Carrier Pin.

 

Insert the Carrier Pin from the left side of the Bolt Carrier. You may need to slightly rotate the Bolt to allow alignment and insertion of the Carrier Pin, or you may need to adjust the position of the Firing Pin. Once fully inserted, the Carrier Pin will protrude on the right side of the Bolt Carrier and will be held in place by its spring and detent mechanism.

 

Finally, slide the flat end of Firing Pin Sleeve onto the Firing Pin within the Carrier – up to the thin indexing mark machined onto the Sleeve. This positions the Firing Pin Sleeve so that the Sleeve Set Screw can be tightened down into the Firing Pin Sleeve’s large groove. Screw in the Sleeve Set Screw and tighten it down – ensuring that the Firing Pin Sleeve cannot be removed from the Carrier. Then screw the Rear Roller Bearing Cap Screw and Bearing into the same hole and tighten.

 

Perform a FUNCTION CHECK on the Firing Pin Safety by keeping pressure on the back of the Firing Pin and rotating the Bolt within the Carrier. With the Bolt completely rotated clockwise (as you look at the Bolt Face), you should see the Firing Pin protruding from its hole in the center of the Bolt Face. Maintain the pressure on the back of the Firing Pin and rotate the Bolt back all the way up - counterclockwise into “locked position” (Cam Pin aligned with Bearings on top of Bolt Carrier). The Firing Pin should go back into the Bolt. If this function check did not work properly then the assembly is incorrect. Disassemble it and reassemble it following the above instructions.

 

Now insert the Bolt Carrier back into the Upper Receiver, by keeping all three Bearings in a straight line, and the Bolt end forward to mate with the Barrel. Push the Bolt Carrier fully into the Upper Receiver, then slide the Bolt Handle and its Sleeve into the Bolt, and rotate the Handle downward until it stops – locking the Carrier into position within the Receiver. With the bend of the Bolt Handle angled down from the Upper, you can then tighten the Bolt Handle Set Screw with the 3/32” Allen Wrench. The Handle should now be tightly locked in position – exhibiting little or no play or rotation. Now the Upper Receiver is ready to be stored in the case, or assembled onto the Lower Receiver in preparation for shooting.

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