ArmaLite AR-50 Rifle Operator Instructions

							P.O. Box 299 Geneseo IL 61254 Tel 309-944-6939 fax 309-944-6949 [email protected] 
                       
 
 
OPERATOR’S INSTRUCTIONS 
for the 
ARMALITE AR-50 RIFLE 
 
April 15, 2002 
 
 
I. INTRODUCTION 
 
Figure 1, 
The AR-50 rifle 
Description: 
  
The AR-50 is a robust, front locked, manually loaded bolt action single-shot rifle 
chambered for the .50 caliber Browning Machine Gun cartridge.  It is intended for long 
range target shooting. 
 
The AR-50 is a finely made rifle, a sophisticated machine built for long years of reliable 
use.  It consists of two major elements, the Barreled Action Assembly and the Stock 
Group.  They are joined at a unique machine-rest style V-block interface.  Accurate, 
repeatable bedding is formed by the engagement of the octagonal Receiver and the deep 
V channel in the aluminum Forestock.  
 
 
  
						

							 
Figure 2      Figure 3   
The ArmaLite .50 Caliber Early Muzzle Brake    The ArmaLite .50 Caliber Muzzle Break 
 
 
The AR-50 is equipped with an extremely effective Muzzle Brake.  It reduces the 
punishing recoil of the .50BMG to a relatively mild shove.  It is effective enough that 
even a small-statured shooter can fire the rifle, and most shooters will be able to spend 
long days at the range without discomfort.  
 
The Muzzle Brake is held in place by both a lock ring and Loc-Tite.  Don’t remove it 
unless replacement or repair is necessary.  Trying to force the Brake off without 
softening the Loc-Tite may unscrew the barrel!  
 
II.  SAFETY FIRST: 
 
Always wear effective hearing protection. The AR-50 is extremely loud due to the 
efficiency of the muzzle brake.  Wear double hearing protection: foam plugs and good 
quality hearing protection muffs.  Assure that spectators and other shooters within 100 
yards of the firing point are also wearing hearing protection.  You
 are responsible for 
warning them that you are about to fire, and that the shot will be loud. 
 
Never fire the rifle without the Muzzle Brake in place.  The Muzzle Brake is an 
important safety device.  It makes the rifle comfortable to shoot and, more importantly, 
prevents the rifle from recoiling hard enough to possibly injure the shooter.  
 
Assure that the Muzzle Brake is firmly secured and undamaged.  Make sure the 
Brake is screwed fully and firmly onto the Barrel.  Make sure that all of the Brake Screws 
(early brake) are in place and fully tightened.  Never fire the rifle if a Screw is missing.  
Never shoot the rifle without the Blast Deflector (the heavy wings behind the brake) in 
place.  Normal tolerances may allow the Deflector of the early brake to be slightly loose. 
 
Make sure that your backstop is fully capable of stopping the powerful .50 BMG 
cartridge.   
 
Avoid muzzle blast.  The AR-50’s Muzzle Brake works by diverting muzzle gasses 
towards the rear.  It is LOUD.  Spectators should not stand within 25 yards of the Rifle, 
and should be especially careful not to stand in the area 30 to 90 degrees to either side of 
the Rifle.  The best place to be is directly to the rear of the Rifle, shooting it.    
						

							 
Use only clean, high quality ammunition, in good condition.  Some.50 caliber 
ammunition is old surplus, and is unreliable and inaccurate.  ArmaLite cannot condone 
the use of handloaded ammunition in the AR-50.  Any such use voids any ArmaLite 
warranty.   
  
Make sure that no cleaning patch or other obstruction is in the Barrel or Muzzle 
Brake.  It may damage the Rifle or flying debris may injure somebody standing nearby. 
 
Keep your ArmaLite in good hands… Yours!  Keep it locked up and secure.  Don’t 
become the victim of a theft, or find your Rifle in the hands of anybody unworthy of it.  
Secure the Bolt separately, or lock the Rifle in a vault. 
 
 
 
 
 
III.  OPERATING INSTRUCTIONS 
 
A.  Controls and Indicators. 
 
        2                                       4 
 
 
                                              5                                                                         3      1 
 
 
Figures 4 and 5 
Operating Controls 
 
1.  Bolt Handle.  Lift the Bolt Handle to unlock the Bolt and pull the Bolt to the rear.  
Pulling back slowly leaves the cartridge in the receiver, pulling quickly ejects it.  The 
AR-50 is a large rifle, and the bolt will be harder to turn than you’re used to.  
						

							2.  Safety.  The Safety is mounted at the rear of the Bolt Group.  To engage the Safety, 
turn the Safety counterclockwise to the 1:30 “safe” position.  To place the Safety to 
“fire,” turn the Safety to the horizontal, 3:00 position. (Note: The AR-50 design allows 
the Striker to shift forward about 1/8 inch if the Safety is engaged and the Trigger is then 
pulled. The Safety is deliberately made difficult to shift from this forward position to the 
fire position with normal finger pressure. The Safety is easily and properly returned to 
the cocked position by raising, then lowering the Bolt Handle.)   
 
3.  Trigger.  The Trigger is located within the Trigger Guard.  It is of conventional, 
single stage design.  Grasp the Grip with the right hand and pull the Trigger straight to 
the rear.  The weight of the striker assembly requires the trigger to be set at a heavier 
weight than is normal on a lighter rifle.  It will not disturb accurate shooting. 
 
4.  Buttplate Locking Screw.  Loosen the Screw with a ¼ inch Allen wrench to raise or 
lower the Buttplate to suit the shooters firing position.  
 
5.  Cheekpiece Locking Screws.  Loosen the screws with a 5/32 inch Allen wrench to 
raise or lower the Cheekpiece.   
 
B.  Maintenance and Safety Checks 
 
1.  Make sure that the Rifle is unloaded, and that the Bolt is to the rear. 
2.  Inspect the bore to make sure that there are no obstructions. 
3.  Inspect the Muzzle Brake to assure that it is tight, all screws are intact, and the Blast 
Deflector is in place. 
4.  Close the Bolt, assuring that the Safety (which is attached directly to the striker) 
remains at the rear, cocked position.   
5.  Engage the Safety.  If the Safety doesn’t engage, the Rifle probably didn’t stay 
cocked.  Have it inspected by a competent gunsmith.  It will tend to require strong effort 
to place the Safety to the “safe” position and, more importantly, to take it off safe. 
6. Rotate the Safety to the 3:00 “fire” position, and pull the Trigger.  The Safety should 
jump forward to the fired position. 
7.  Raise the Bolt Handle, making sure that the Safety shifts to its rear position. 
Pull the Bolt to the rear.  You are now ready to load and fire. 
 
C.  Loading and Firing 
 
1.  Verify safety.  Make sure that the Rifle is pointed in a safe direction, towards a 
known, adequate backstop.  Make sure that everybody within 100 yards knows that the 
rifle is about to be fired and protects their hearing. 
2.  If it’s not already open, raise the Bolt Handle and pull the Bolt to the rear. 
3.  Place a Cartridge into the Action through the Ejection Port. 
4.  Close the bolt to chamber and lock the Cartridge.  Push the Bolt forward forcefully so 
that the Extractor snaps over the case rim.  You will feel fairly strong resistance as the 
Ejector is pressed back into the face of the bolt.  Turn the Bolt handle down completely. 
5.  Assume a good position behind the rifle.  Make sure that the Buttplate is locked at a 
level that allows it to rest in complete contact with the shoulder.  Make sure that the 
cheek is well forward on the Cheek Rest. 
6.  Aim at the target,   
7.  Pull the Trigger straight to the rear.  You will know when the rifle fires. 
  
						

							Note:  the AR-50 is equipped with a very secure manual Safety.  ArmaLite recommends 
loading the rifle immediately before firing a shot instead of leaving the rifle loaded and 
on safe. As a practical target shooting measure, the Rifle should be considered safe only 
when it is unloaded and the action is open.  
 
 
Emergency Procedures.  If the Rifle fails to fire when the Trigger is pulled: 
 
1.  Wait 15 seconds to allow a possible “hangfire” to go off then...   
2.  Check to see if the Safety is engaged by mistake.  If so, raise and then lower the Bolt 
Handle to assure the Striker is reset, rotate the Safety to the 3:00 “fire” position, and fire. 
3.  If the rifle still doesn’t fire, be cautious and assume the cartridge will discharge when 
the bolt is opened and move from behind the action.  Wait another 15 seconds to allow a 
possible hangfire to discharge, and open the Bolt smartly and unload the Rifle.   
4.  Examine the Rifle carefully to identify the cause of the malfunction, and correct it. 
 
MAINTENANCE INSTRUCTIONS 
 
A.  Disassembly. 
 
1.  Assure that the Rifle is unloaded, and engage the Safety. 
 
 
Figures 6 and 7 
Removing the Bolt Group 
 
2.  Remove the Bolt Group.  Use a 3/16 inch Allen wrench to loosen, then remove the 
button headed Bolt Stop Screw at the left rear of the Receiver.  Pull the Bolt Group to the 
rear and out of the Receiver.  Further disassembly of the Bolt Group should be done only 
for repair or lubrication.   
 
Figure 8 
Removing the Extractor 
  
						

							3.  Removing the Extractor.  Use a small diameter pin punch to press the Extractor 
Plunger to the rear.  At the same time, pull the Extractor straight out of the side of the 
Bolt.  It helps to have three small hands or a few extra fingers.  Caution:  The Extractor 
Spring Plunger is under spring pressure.  Failure to control the Spring and Plunger 
may cause injury. 
 
Figures 9 and 10 
Removing the Bolt Sleeve and Striker Group 
 
3. Removing the Bolt Sleeve and Striker Group.  With the Safety still engaged, unscrew 
the Bolt Sleeve and remove the entire group.  The Bolt is equipped with ArmaLite’s 
exclusive Floating Bolt Head.  It is intentionally designed to flex to assure that all 
three lugs bear properly against their locking surfaces.   
 
4. Push out the Bolt Retaining Pin to remove the Bolt Head from the Bolt Body.  The 
Bolt Handle may be removed at the same time. 
 
      
 
Figure 11, 12 & 13     
Removing Bolt Retaining Pin to Remove Bolt Head 
 
Figure 14 
Disassembling the Bolt Sleeve and Striker Group 
  
						

							6.  Disassembling the Bolt Sleeve and Striker Group.  This is tricky and should not be 
done unless replacing a part, like a broken striker. 
 
Use a 4 x 4 inch piece of wood with a ¼ inch diameter hole through the center as a tool.  
Push the Striker tip (commonly called the firing pin) into the hole until the Striker Spring 
starts to compress.  This will allow the Safety to be rotated to about the 12:00 position on 
the Sleeve, exposing the Safety Pin.  Push the Safety Pin out while carefully controlling 
the Sleeve to prevent it, the Safety, and the Spring from flying apart.  Carefully ease the 
pressure on the Sleeve to allow the Spring to expand under firm control.  Once the Spring 
is released, the Striker Pin can be drifted out to replace the Striker.  Caution:  The entire 
Bolt Sleeve and Striker Group are under spring pressure.  Failure to control the 
parts may result in injury.  It should very seldom be necessary to disassemble these 
parts. 
 
6.  Removing the Action Assembly.   
 
Remove the telescopic sight and the Cheekpiece.  
 
 
Figure 15 
Loosening the Bedding Wedge 
 
Loosen the Bedding Wedge at the front of the Action by loosening the Button Headed 
Wedge Screw under the action using a 3/16 inch Allen wrench.  
 
 
 
Figure 16 
Removing the Grip Frame 
 
Place the rifle upside down. Remove the Grip Frame by removing the Grip Frame Screw, 
using a 3/16 inch Allen screw.  Pull the Grip Frame from the Forestock.  
  
						

							Remove the two Action Screws from the bottom of the Forestock using a ¼ inch Allen 
wrench.  Lift the Stock Assembly straight off the Action. 
 
 
Figures 17 and 18 
Removing the Buttstock 
 
5. Removing the Buttstock from the Forestock.  Remove the 2 or 3 Buttstock Screws at 
the right rear of the Forestock using a 5/32 inch Allen wrench.  Pull the Buttstock down 
and to the rear to remove it. 
 
 
 
       
Figure 19 & 20 
Removing the Trigger Group 
 
 
8. Removing the Trigger Group.  Drift the two Trigger Group Pins out of the receiver to 
remove the Trigger Group.  The Trigger Group is not user-serviceable. 
 
9.  Removing the Muzzle Brake.  The Muzzle Brake is held in place by its Lock Ring and 
Loc Tite.  It is not intended to be readily removable.  
 
B. Reassembly.  Reverse the steps above.  Tighten the Action Screws very lightly.  
Tighten the Draw Bolt at the front of the Action by tightening the front screw before final 
tightening the other two Action Screws.  This assures that the Recoil Lug is seated 
properly. 
 
C. Cleaning.    
						

							 
Improper cleaning ruins more firearms than shooting does.  The AR-50 will provide 
years of use with minimal cleaning and preservation. 
 
Wipe the rifle free of dust with a dry rag.  Further clean the surface with a rag bearing a 
small amount of solvent.  Pay particular care to the interior of the Action.  It should 
seldom be necessary to remove the Bolt for cleaning. 
 
Use a pull-through device to clean the bore.  Use a .50 caliber bore brush soaked with a 
good bore solvent.  Pull it from the breech to the muzzle several times. 
 
Pull a closely fitting patch soaked with solvent through the bore from the breech to the 
muzzle.  Follow the solvent maker’s instructions regarding soaking or waiting times.  
Make sure that the patch is small enough to avoid being caught in the Muzzle Brake.  
Pull dry patches through the bore in a similar manner to remove the solvent and dirt from 
the bore.  Preserve the bore with a generous oiling.  Apply the oil by pulling an oily patch 
trough the bore from breech to front. 
 
Oil or lightly grease the narrow track under the Cheekpiece at the top of the Buttstock.  
The Sear surface of the Striker runs through this track and serves as a rear bolt guide.  A 
“Q-Tip” or other such device will suffice. 
 
Heat treat processes may produce dark areas of phosphate at the breech ring and bolt 
cam.  This is normal. 
 
D. Preservation.  Wipe the entire rifle with a slightly oily rag.  Make sure that the bore 
is well oiled.  Store in a container that contains no foam.  (Foam absorbs moist air.  
Heating the container may drive moisture from the foam.  It can then condense on a cool 
rifle.)  Use a desiccant or Vapor Phase Inhibitor in the container to help prevent rust.  
 
V.  INSTALLATION OF ACCESSORIES 
 
A.  Telescopic Sight Base 
 
Two optional scope bases are available from ArmaLite.  Each is specially made with 
special recoil lugs designed to defeat both lateral and longitudinal recoil forces and to 
engage the scope mounting holes on the receiver.  One provides 15 minutes of elevation 
to an attached scope mount for use at ranges out to 1000 yards.  The other provides 50 
minutes of elevation to allow shooting at ranges up to 1500 yards.  Each is designed to 
accept ArmaLite’s scope mounts, as well as most other Weaver type rings. 
 
Both bases are supplied with four Allen screws for attachment to the base.  Because of 
the angle of the base, at least three of the screws must be shortened so that they don’t 
protrude into the bolt track of the receiver.  To install the bases: 
  
						

							 
Figure 21 
The Scope Base 
 
1.  Remove the bolt group as instructed above. 
2.  Set the scope base on the receiver, with the recoil lugs of the base engaging the slots 
of the receiver.  The high end of the base must be to the rear. 
3.  Insert the rear screw and tighten it.  Feel inside the receiver to determine if the screw 
passes all the way through the receiver roof.  If it does, shorten the screw until it won’t 
protrude. 
4.  Repeat the process with the other screws.     
5.  You may apply Loctite or another thread cement to the screw threads if you wish.  It is 
not necessary.  
 
 
Figure 22 
Attaching the ArmaLite Scope Mount 
 
B. Attaching the ArmaLite Scope Mount or Rings:  The Scope Mount will accept 
ArmaLite Mounts or Rings.  They are equipped with a positioning cross-rail.  Select a 
location on the Scope Rail, and attach the Scope Mount with the cross-rail engaging a 
slot in the rail.  Tighten the Mount or Rings securely:  they are held in place by the grip 
of the Side Rail. 
 
 
C. Bipod Adapter 
 
The AR-50 must be fired from a rest or bipod.  An optional bipod adapter is available 
with which to mount Harris or other bipods.  To install the bipod adapter: 
 
1.  Screw the sling swivel lug into the adapter, stopping with the hole in the lug is at right 
angles to the adapter.