THE BOSS™ AND YOUR MODEL 70. (BALLISTIC OPTIMIZING SHOOTING SYSTEM)
These are additional instructions specific to your BOSS™ equipped Model 70 rifle. Please read and understand the cautions and proper handling procedures outlined in this booklet and in your Model 70 owner’s manual, before using your new BOSS equipped rifle. Ifyou are missing the operating manual for your rifle, we will send you a free manual on request.
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.
The Model 70 is considered by many to be the most perfectly designed rifle ever. The Model 70 is a rifle ofhistory and unequalled modern performance — especially with the revolutionary BOSS. U.S. Repeating Arms Co. is excited to offer this incredible new patented technology on the Winchester Model 70.
The BOSS gives the Model 70 a degree of accuracy found only on expensive custom rifles. The Model 70 offers the rifleman the best of two worlds: traditional craftsmanship and the latest in modern rifle technology. Now, more than ever, it is truly “The Rifleman’s Rifle.”
HOW THE BOSS™ WORKS
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
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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 allowsyou 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.
MUZZLE BRAKE FEATURE
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.
BOSS SPECIFICATIONS
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.
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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.
THE “SWEET SPOT”
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.
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PRELIMINARY ADJUSTMENTS
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).
TUNING YOUR RIFLE TO THE “SWEET SPOT”
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 locknut. (Refer to Figure 4.) To set the “sweet spot,” the
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