Winchester Repeating Arms BOSS User Manual
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. If you 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 PRO-
VIDES 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 of history 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 consis
tently 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 shoot
ing or flyers caused by low quality bullets and ammuni
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tion.
TO OBTAIN THE HIGHEST LEVEL OF ACCU
RACY FROM YOUR RIFLE IT IS RECOMMEND
ED THAT THE RIFLE BORE BE CLEANED
EVERY 25 TO 30 ROUNDS. SEE “CLEANING
THE RIFLE BORE” SECTION OF THIS BOOK
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LET FOR CLEANING PROCEDURES.
MUZZLE BRAKE F
EATURE
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 per-
sons nearby, as muzzle blast, debris and ejecting shells
could inflict serious injury.
BOSS SPECIFICATIONS
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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 cal
ibers 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 CUR
RENTLY AVAILABLE CALIBERS. SWITCHING
BOSS COMPONENTS FROM DIFFERENT CAL
IBERS 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.
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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 sep
arate 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
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.
800-945-1392. “Sweet spot” settings were
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PRELIMINARY A
DJUSTMENTS
Before adjusting your rifle to the “sweet spot,” it is impor
tant 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 microm
eter 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
-
10 and inscribed on the barrel of your rifle. Smaller,
0
1/10 turn increments are inscribed at the rear of the lock
nut. (Refer to Figure 4.) To set the “sweet spot,” the
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