WARNING: THE “BOSS” INCLUDES A RECOIL REDUCING MUZZLE BRAKE WHICH PROVIDES SUBSTANTIAL INCREASED NOISE / MUZZLE BLAST. ALWAYS WEAR HEARING PROTECTION TO PREVENT HEARING LOSS OR DAMAGE. 

CAUTION: THE THREADING ON YOUR BARREL IS FOR COMPONENTS FOR THE U.S. REPEATING ARMS CO. BOSS ONLY. DO NOT INSTALL ANY OTHER DEVICE ONTO THE WINCHESTER MODEL 70 BOSS BARREL. DO NOT INSTALL THE BOSS DEVICE ON ANY RIFLE WHICH IS NOT DESIGNED AND FITTED FOR THE BOSS BY U.S. REPEATING ARMS CO. DOING SO MAY CAUSE SERIOUS INJURY OR DEATH TO YOURSELF OR OTHERS. 

Barrel vibrations are the primary cause of rifle inaccuracy. Every time a rifle is fired, barrel vibrations are set in motion. These vibrations occur in all directions, even back and forth along the axis of the barrel. They are influenced by many factors such as bullet type, bullet weight, primers, different powders and even barrel configurations. 

The BOSS (Ballistic Optimizing Shooting System) is an adjustable weight that alters rifle barrel vibrations. By adjusting the weight on the BOSS, you can tune your rifle to specific ammunition, allowing a bullet to consistently exit the rifle muzzle at the optimum point in barrel vibration. At this optimum point, either at the peak or valley of a vibration wave, the rifle barrel is momentarily motionless. The suggested “sweet spots” (found on a separate sheet supplied with this manual) are the starting points for determining the optimum accuracy of your BOSS equipped Model 70. Once the true “sweet spot” is determined for a given ammunition, your rifle will consistently deliver extraordinarily tight groups. The BOSS allows you to tune your rifle to your ammunition to get the optimum accuracy for all available factory loads. 

When adjusted to the “sweet spot,” the BOSS will compensate for slight deviations in ammunition velocity. The BOSS will not, however, compensate for poor shooting or flyers caused by low quality bullets and ammunition. 

TO OBTAIN THE HIGHEST LEVEL OF ACCURACY FROM YOUR RIFLE IT IS RECOMMENDED THAT THE RIFLE BORE BE CLEANED EVERY 25 TO 30 ROUNDS. SEE “CLEANING THE RIFLE BORE” SECTION OF THIS BOOKLET FOR CLEANING PROCEDURES. 

The unique exhaust hole pattern on the BOSS provides considerable recoil reduction. Recoil reduction of the BOSS ranges from 30% to 50% — depending on caliber, weight of rifle, etc. 

You will experience an increase in noise and concussion (muzzle blast) when a BOSS equipped rifle is fired. Hearing protectors (shooting ear plugs or muffs) should always be worn to guard against hearing damage when shooting a BOSS equipped rifle. Wear shooting glasses to protect your eyes from flying particles. Always keep a safe distance between the muzzle of your firearm and any persons nearby, as muzzle blast, debris and ejecting shells could inflict serious injury. 

The BOSS body length is 2 inches for most calibers. The size of the gas vent holes and hole pattern is the same for most calibers. The size of the bullet exit hole is the same for all calibers except for the 338 Win. Mag. The thread system for the 338 Win. Mag. is different from other calibers to rule out the possibility of accidentally or deliberately switching components and creating an unsafe combination. 

WARNING: THE .338 CALIBER BOSS HAS A LARGER EXIT BORE THAN ALL OTHER CURRENTLY AVAILABLE CALIBERS. SWITCHING BOSS COMPONENTS FROM DIFFERENT CALIBERS TO THE .338 BARREL COULD CAUSE A RESTRICTION OR OBSTRUCTION RESULTING IN POSSIBLE INJURY OR DEATH TO THE SHOOTER OR OTHERS. 

Each BOSS consists of a micro-adjustable locknut and body (See Figure 1). The body of the BOSS consists of a weight and muzzle brake. The weight and muzzle brake are affixed by LOCTITE®. To obtain the utmost accuracy from your BOSS equipped Model 70 it is very important that the micro-adjustable locknut and body are fully tightened before firing. 

Precision accuracy is achieved by calibrating your rifle caliber and ammunition with a “sweet spot” setting. The “sweet spots” for your Model 70 are found listed on a separate sheet supplied with this manual. If you are missing the “sweet spot” sheet or if there is no “sweet spot” listing for your rifle caliber or ammunition, call U.S. Repeating Arms Co. at 1-800-945-1392. “Sweet spot” settings were determined through extensive testing by US. Repeating Arms Co. Research and Development staff. “Sweet spots” may vary between rifles of identical specifications with a given ammunition. Even one quarter of a turn away from the “sweet spot” can cause a group to spread as much as one inch or more. We suggest you use our suggested “sweet spot” setting as a starting point in determining the exact “sweet spot” setting for your particular rifle and make adjustments accordingly. Note: any change in BOSS setting may slightly alter your rifle’s point of impact. It’s recommended you set the BOSS “sweet spot” setting before sighting in your rifle for windage and elevation. The BOSS was tested in full turn, 1/2 and 1/4 turn increments. Tighter groups may be achieved with the BOSS tested in other positions. 

Before adjusting your rifle to the “sweet spot,” it is important that your BOSS is calibrated with the barrel. This will ensure that your rifle is consistent with those tested by U.S. Repeating Arms Co. Research and Development when BOSS suggested “sweet spots” were determined. 

To find out if your BOSS needs to be calibrated, loosen the micro-adjustable locknut until it bottoms out on the threads of the BOSS — or will not loosen any further. If your BOSS is calibrated, the “0” on the micrometer adjustment ring will line up with the longitudinal hatch mark on the barrel (See Figure 2). 

If the “0” isn’t aligned with the longitudinal hatch mark, you will need to calibrate your BOSS. Move the micrometer adjustment ring, on the bottom of the locknut, so that when bottomed out on the threads the “0” is aligned with the vertical hatch mark. To adjust the micrometer adjustment ring, insert your fingernail or a small pointed object in the split of the ring and simply rotate the ring (See Figure 3).

Full turn “sweet spot” setting or graduations are numbered 0-10 and inscribed on the barrel of your rifle. Smaller, 1/10 turn increments are inscribed at the rear of the lock nut. (Refer to Figure 4.) To set the “sweet spot,” the micro-adjustable locknut is turned either clockwise or counterclockwise until it rests on the desired “sweet spot” number inscribed on your rifle’s barrel. One full revolution of the locknut indicates one full change in setting or one index mark on the barrel. 1/10 turn increments are set by turning the micro-adjustable locknut until the desired setting lines up with the longitudinal hatch mark on the barrel. IMPORTANT: When adjusting the “sweet spot” make sure you grip the knurled surface of the micro-adjustable locknut. The knurled portion of the locknut and micrometer adjustment ring must rotate together to ensure a precise “sweet spot” setting and retainment of proper calibration. 

CAUTION: WHEN SETTING THE “SWEET SPOT” ON YOUR RIFLE MAKE CERTAIN YOUR RIFLE IS FULLY UNLOADED AND THAT THE RIFLE’S SAFETY IS IN THE “ON SAFE” POSITION AND YOUR RIFLE IS POINTED IN A SAFE DIRECTION. 

THE SUGGESTED “SWEET SPOTS” FOR YOUR MODEL 70 ARE LISTED ON A SEPARATE SHEET SUPPLIED WITH THIS MANUAL. IF YOU ARE MISSING THE “SWEET SPOT” SHEET OR IF YOUR RIFLE’S CALIBER OR AMMUNITION IS NOT ON THE LIST, CALL U.S. REPEATING ARMS CO. AT 1-800-782-4440.

EXAMPLE 1 - 

1. Suppose you have a 270 caliber Model 70 and are sighting in with 150 gr. cartridges. Referring to the “sweet spot” chart you will find the average “sweet spot” is 2.5 for a 270 caliber with 150 gr. ammo.

2. After having made sure your BOSS is calibrated, rotate the locknut counterclockwise two and one half full revolutions. The edge of locknut should line up or rest on the marking for 2 on the barrel.

NOTE: It is not necessary to calibrate your BOSS on the barrel with every change in “sweet spot” setting. However, you should check your BOSS periodically to assure that it is aligned. 

3. Since the “sweet spot” is listed as 2.5, the 5 inscribed on the micrometer adjustment ring should line up with the hatch mark on the barrel (See Figure 4).

4. Tighten the body of the BOSS so it is secure against the locknut. Use the special wrench supplied with your rifle (see Figure 5).

CAUTION: REMOVE THE WRENCH BEFORE FIRING YOUR RIFLE. 

EXAMPLE 2 - 

1. Suppose you have a 30-06 Sprg. Model 70 with 150 gr. cartridges. Referring to the “sweet spot” chart you will find the average “sweet spot” is 1.8.

2. Adjust your BOSS and rotate the micro-adjustable locknut counterclockwise until the edge of the locknut lines up or rests on the marking for 1 on the barrel.

3. Since the “sweet spot” is listed as 1.8, the 8 inscribed on the micrometer adjustment ring should line up with the hatch mark on the barrel (See Figure 6).

4. Using the special wrench, tighten the body of the BOSS so it is secure against the locknut. Your BOSS system is now calibrated for 150 gr. ammo for 30-06 Sprg.

If you desire to obtain even tighter groupings, turn the micro-adjustable locknut 1/4 of a turn clockwise from the “sweet spot,” and fire your rifle at your target. If groups open up, turn the locknut counterclockwise and shoot at different 1/4 turn settings until you are satisfied with your groupings. Again, “sweet spots” may vary between rifles of identical specifications with a given ammunition. As in any sighting-in process, best results are obtained through trial and error. You may need to retune the BOSS should you decide to shoot different brands, lots and types of ammunition. 

Be sure to keep a record of your rifle’s “sweet spots,” especially if you use your rifle for different game and shoot different loads.

CAUTION: WHEN ADJUSTING THE SWEET SPOT NEVER SET THE BOSS BEYOND THE 10 SETTING ON THE BARREL. 

With the BOSS set beyond 10, the BOSS could become loose, misaligned or fall off when firing the rifle. This could result in serious injury to yourself or others. 

IMPORTANT: Each time you set the “sweet spot,” the body of the BOSS must be tight against the micro-adjustable locknut. Failure to keep the components tightly locked will adversely affect accuracy. NOTE: The action mounting screws on your Model 70 should be fully tightened (See Figure 7). If the screws are loose, tighten the front screw first, then the rear trigger guard screw. Always leave the middle screw “snug, hand tight” only. 

The BOSS is a precision instrument. 

IN ORDER FOR THE BOSS TO OPERATE EFFECTIVELY IT IS VERY IMPORTANT YOUR RIFLE REMAINS IN THE SAME CONDITION IT WAS PURCHASED. IT IS ABSOLUTELY NECESSARY FOR YOUR RIFLE’S BARREL TO REMAIN FREE-FLOATING AND PROPERLY BEDDED. 

To check for adequate clearance, it is recommended that a piece of paper, folded once, be able to pass between the barrel and stock without any interference. If the barrel is not free-floating, take your rifle to a competent gunsmith or send it to U.S. Repeating Arms Co. Service Center. Special bedding of the action on your BOSS equipped Model 70 rifle is installed at the factory and aids greatly in improving accuracy. If you have any modifications done to your stock, make sure the bedding has not been altered. If the bedding on your rifle has been modified send your rifle to a U.S. Repeating Arms Co. Service Center. 

To maintain utmost accuracy from your BOSS equipped rifle, or any rifle, extensive testing has proven that the rifle bore must be cleaned every 25 to 30 rounds. 

CAUTION: BEFORE CLEANING YOUR RIFLE MAKE CERTAIN YOUR RIFLE IS FULLY UNLOADED, THE MAGAZINE IS UNLOADED / REMOVED, THE SAFETY IS IN THE “ON SAFE” POSITION AND YOUR RIFLE IS POINTED IN A SAFE DIRECTION. 

We highly recommend that your rifle be cleaned with the BOSS installed on your barrel. Remove the bolt and clean from the breech end. 

Modern cartridge jackets are made mainly of copper and zinc. These metals glide easier and increase barrel life, however, residues from copper and zinc also stick to the barrel and require more frequent cleaning. As top bench rest shooters have known for decades, copper solvent is the key to cleaning a barrel for optimum accuracy. The recommended cleaning procedure is as follows: 

1. Clean the bore with a good powder solvent to remove all traces of powder residue. Performing this step before the application of a copper solvent will prevent the bore from refouling with copper so readily. 

2. Swab the bore with a good copper solvent using the manufacturer’s recommended procedure. After neutralizing the solvent, generally with oil, it is important to swab the bore dry. Swabbing the bore dry will reduce copper buildup.

NOTE: DO NOT USE SOLVENTS OF DIFFERENT MANUFACTURERS CONCURRENTLY. A CHEMICAL REACTION MAY RESULT THAT WILL CORRODE EVEN STAINLESS STEEL BARRELS. IT IS IMPORTANT TO FOLLOW THE MANUFACTUR- ER’S RECOMMENDATIONS EXACTLY. 

3. If absolutely necessary, the BOSS may be removed to facilitate cleaning.

Clean the BOSS by removing the locknut and body from the rifle. With the components disassembled, wipe each component with oil. Lightly oil all threads and make sure exhaust holes on the body of the BOSS are free of obstructions. 

4. Reassemble your BOSS by screwing on the micro-adjustable locknut then the BOSS body. After taking apart the BOSS it will be necessary to reset the “sweet spot” and it may be necessary to recalibrate the BOSS.

MAKE CERTAIN ALL CLEANING PATCHES ARE REMOVED FROM THE BARREL AND EXHAUST HOLES IN THE BODY OF THE BOSS BEFORE FIRING YOUR RIFLE. 

5. When firing for extreme accuracy, after cleaning the bore it is recommended two fouling shots be fired before shooting for accuracy. Additionally, it is recommended the rifle be allowed to cool every three rounds.

If your “Sweet Spot” listing card is missing from this manual, or if your caliber is not listed, call U.S. Repeating Arms Company for information: 1-800-7820-4440. 

As a gun owner, you accept a set of demanding responsibilities. How seriously you take these responsibilities can mean the difference between life and death. Failure to follow any of these instructions can cause extensive damage to your gun and/or possible serious injury or death to yourself and others. There is no excuse for careless or abusive handling of any firearm. At all times handle any firearm with intense respect for its power and potential danger.  

PLEASE READ AND UNDERSTAND ALL OF THE CAUTIONS, PROPER HANDLING PROCEDURES AND INSTRUCTIONS OUTLINED IN THE OWNER’S MANUAL BEFORE USING YOUR NEW FIREARM. 

1 - ALWAYS KEEP THE MUZZLE OF YOUR FIREARM POINTED IN A SAFE DIRECTION EVEN THOUGH YOU ARE CERTAIN IT IS UNLOADED. Never point any firearm at anything you do not intend to shoot. Be extremely alert and aware of all persons and property within the range of your ammunition.

2 - NEVER RELY TOTALLY ON YOUR FIREARM'S MECHANICAL “SAFETY” DEVICE.

The word “safety” describes a firearm’s trigger block mechanism, sear block mechanism, hammer block mechanism, or firing pin block mechanism. Mechanical “safeties” are designed to place your firearm in a safer status, and no guarantee can be made that the firearm will not fire even if the “safety” is in the on safe position. Mechanical “safeties” merely aid safe gun handling and are no excuse for pointing your firearm’s muzzle in an unsafe direction. See “Operation of the Safety” section below for instructions on the operation of this firearm’s “safety.”

LIKE ANY MECHANICAL DEVICE, A "SAFETY" CAN SOMETIMES FAIL; IT CAN BE JARRED OR INADVERTENTLY MANIPULATED INTO AN UNSAFE CONDITION.

Mechanical "safeties" merely aid safe gun handling and are no excuse for pointing your rifle's muzzle in an unsafe direction.

While it is a good idea to "test" your rifle's mechanical "safeties" periodically for proper function, NEVER TEST IT WHILE YOUR RIFLE IS LOADED OR POINTED IN AN UNSAFE DIRECTION

Safe gun handling does not stop with your gun's mechanical "safety devices -- it starts there. Always treat your rifle with the respect due a loaded, ready-to-fire firearm.

3. WHENEVER YOU HANDLE A FIREARM, OR HAND IT TO SOMEONE, ALWAYS OPEN THE ACTION IMMEDIATELY, VISUALLY CHECK YOUR RIFLE'S CHAMBER, FEED MECHANISM AND MAGAZINE.

Make certain they do not inadvertently contain any ammunition. Always keep the chamber empty and "safety" in the "on safe" position unless shooting is imminent.

4. DO NOT TRANSPORT YOUR RIFLE LOADED, WHETHER IN A SCABBARD, GUN CASE, OR OTHER CONTAINER.

5. HUNTING FROM ELEVATED SURFACES SUCH AS TREE STANDS IS DANGEROUS, and may increase the risk of handling a firearm. The following rules should always be observed by you and those you hunt with: Always make certain that the stand being used is safe and stable. Always make certain that your firearm is unloaded when it is being taken up to and down from the stand. Always make certain that your firearm is not dropped from the stand, or dropped while it is being taken up to or down from the stand. Remember, a loaded firearm may discharge when dropped, even with the safety in the "on safe" position.

6. BEWARE OF BARREL OBSTRUCTIONS, for the safety of both your gun and yourself. Mud, snow, and an infinite variety of other obstructions may inadvertently lodge in a barrel bore. It takes only one small obstruction to cause dangerously increased pressures that can ruin (swell or rupture) the finest rifle barrels.

BEFORE CHECKING FOR A BARREL OBSTRUCTION, BE CERTAIN NO LIVE ROUND IS IN THE CHAMBER AND THAT THE MAGAZINE IS REMOVED AND FEED MECHANISMS ARE COMPLETELY EMPTY. PLACE THE "SAFETY" IN THE "ON SAFE" POSITION.

Look through the barrel to be sure it is clear of any obstruction. If an obstruction is seen, no matter how small it may be, clean the bore with a cleaning rod and patch as described in "Cleaning and Maintenance Suggestions." Before the first firing, clean the bore with a cleaning rod and patch, and wipe away any anti-rust compound in the action / chamber areas.

7. ALWAYS UNLOAD YOUR RIFLE WHEN NOT IN USE. REFER TO "UNLOADING THE RIFLE" FOR AN EXPLANATION OF HOW TO UNLOAD YOUR RIFLE PROPERLY.

As a safety precaution, it is preferable to disassemble your gun for storage. Store your gun and ammunition separately -- well beyond the reach of children. Take all safeguards to ensure your rifle does not become available to untrained, inexperienced or unwelcome hands.

8. USE THE PROPER AMMUNITION.

The barrel and action of this rifle have been made with substantial safety margins over the pressures developed by established American commercial loads. Nevertheless, Browning assumes no liability for incidents which occur through the use of cartridges of nonstandard dimensions which develop pressures in excess of commercially available ammunition with standards established by the Sporting Arms and Ammunitions Manufacturers' Institute (SAAMI).

BE ALERT TO THE SIGNS OF AMMUNITION MALFUNCTION.

If you detect an off sound or light recoil when a cartridge s fired, DO NOT LOAD ANOTHER CARTRIDGE INTO THE CHAMBER. Open the action and remove all cartridges from the magazine, chamber and action areas. With the action open, glance down the barrel to make sure that an obstruction does not remain in the barrel. If there is an obstruction, completely clear the barrel before loading and firing again. Failure to follow these instructions can cause extensive damage to your gun and possible serious injury to yourself and others.

MAKE SURE OF ADEQUATE VENTILATION IN THE AREA THAT YOU DISCHARGE A FIREARM. WASH HANDS THOROUGHLY AFTER EXPOSURE TO AMMUNITION OR CLEANING A FIREARM.

Lead exposure can be obtained from discharging firearms in poorly ventilated areas, cleaning firearms or handling ammunition. Lead is a substance that has been known to cause birth defects, reproductive harm and other serious injury.

9. DO NOT SNAP THE FIRING PIN ON AN EMPTY CHAMBER -- THE CHAMBER MAY NOT BE EMPTY!

Treat every gun with the respect due a loaded gun, even though you are certain the gun is unloaded.

10. KEEP FINGERS AWAY FROM THE TRIGGER WHILE UNLOADING, LOADING, UNTIL YOU ARE READY TO SHOOT.

11. BE SURE OF YOUR TARGET AND BACKSTOP.

Particularly during low light periods. Know the range of your ammunition. Never shoot at water or hard object.

12. ALWAYS UNLOAD YOUR RIFLE'S CHAMBER BEFORE CROSSING A FENCE, CLIMBING A TREE, JUMPING A DITCH OR NEGOTIATING OTHER OBSTACLES.

Refer to "Unloading The Rifle" for instructions on the unloading of your rifle. Never place your loaded rifle on or against a fence, tree, car or other similar object.

13. WEAR EYE AND EAR PROTECTION WHEN SHOOTING.

Unprotected, repeated exposure to gunfire can cause hearing damage. Wear ear protectors (shooting ear plugs or muffs) to guard against such damage. Wear shooting glasses to protect your eyes from flying particles. Allow proper distance (eye relief) between the scope and your eye when firing a scoped rifle or shotgun. Always keep a safe distance between the muzzle of your firearm and any persons nearby, as muzzle blast, debris and ejecting shells could inflict serious injury. Also, wear eye protection when disassembling and cleaning your shotgun to prevent the possibility of springs, spring-tensioned parts, solvent or other agents from contacting your eyes.

14. DROPPING A LOADED GUN CAN CAUSE AN ACCIDENTAL DISCHARGE even with the "safety" in the "on safe" position. Be extremely careful while hunting or during any shooting activity, to avoid dropping any firearm.

15. IF YOUR RIFLE FAILS TO FIRE, KEEP THE MUZZLE POINTED IN A SAFE DIRECTION. Hold this position for a minimum of 30 seconds. Carefully open the action and remove the cartridge. If the primer is indented, the cartridge should be disposed of in a way that cannot cause harm. If the primer is not indented, your firearm should be examined by a qualified gunsmith and the cause of the malfunction should be corrected before further use.

16. BE DEFENSIVE AND ON GUARD AGAINST UNSAFE GUN HANDLING AROUND YOU AND OTHERS.

Don't be timid when it comes to gun safety. If you observe other shooters violating any of these safety precautions, politely suggest safer handling practices.

17. BE CERTAIN YOUR RIFLE IS UNLOADED BEFORE CLEANING. Because so many gun accidents occur when a firearm is being cleaned, special and extreme care should be taken to be sure your gun is unloaded before disassembly, cleaning and reassembly. Keep ammunition away from the cleaning location. Never test the mechanical function of any firearm with live ammunition.

18. TEACH AND SUPERVISE FIREARMS SAFETY TO ALL MEMBERS OF YOUR FAMILY --ESPECIALLY TO CHILDREN AND NONSHOOTERS.

Closely supervise newcomers to the shooting sports. Encourage enrolling in hunting/shooting safety courses.

19. NEVER DRINK ALCOHOLIC BEVERAGES OR TAKE ANY TYPE OF DRUGS BEFORE OR DURING SHOOTING.

Your vision and judgment could be dangerously impaired, making your gun handling unsafe to you and to others.

20. READ AND HEED ALL WARNINGS in this instruction book, on ammunition boxes and with all accessories that you install on your firearm. It is your responsibility to secure the most up-to-date information on the safe handling procedures of your Browning gun. Browning assumes no liability for incidents which occur when unsafe or improper gun accessories or ammunition combinations are used.

21. PERIODIC MAINTENANCE -- AVOID UNAUTHORIZED SERVICING.

Your rifle is a mechanical device which will not last forever, and as such, is subject to wear and requires periodic inspection, adjustment and service. Browning firearms should be serviced by a Browning Recommended Service Center or by Browning's service facility in Arnold, Missouri. Browning cannot assume any responsibility for injuries suffered or caused by unauthorized servicing, alterations or modifications of Browning firearms.

22. BROWNING RESERVES THE RIGHT TO REFUSE SERVICE ON FIREARMS THAT HAVE BEEN ALTERED, ADDED TO OR SUBSTANTIALLY CHANGED.

Removal of metal from barrel(s), or modification of the firing mechanism and/or operating parts may lead to Browning's refusal of service on such firearms. Browning will charge the owner parts and labor to return the firearm to original Browning specifications.

DO NOT, UNDER ANY CIRCUMSTANCES, ALTER THE TRIGGER, SAFETY OR PARTS OF THE FIRING MECHANISM OF THIS OR ANY OTHER FIREARM. FAILURE TO OBEY THIS WARNING MAY RESULT IN INJURY OR DEATH TO YOURSELF OR OTHERS.