Shooting Sports USA - January 2018 - 26

PHOTOS BY JOHN PARKER

FEATURE | SIGHTING

Keep both your gun and scope out of the sun before
sighting-in for better group consistency.

internal ballistics and adversely affects shot-toshot velocity-thus degrading accuracy. This
can become critical or even dangerous if the
ammunition is loaded at top velocity/pressure
(hot) to begin with. Handloaders be aware.
Direct sun on exposed ammunition will
always cause groups to open up big time. This
may not be such a big deal in 100- or 200-yard
shots-but at longer ranges it can really affect
accuracy. Years (okay, decades) ago when
I was competing in National Match Course
competition I tested this. I heated some .308
Win. cartridges for my M1A to 160° F in no
time (10 minutes in a 90° F day) thanks to the
summer sun directly on the cartridges. I kept
a second batch in the shade. At 300 yards the
160° F cartridge case heated ammo opened to
nearly 8 inches while the much cooler shade

26

JANUARY 2018 | SSUSA.ORG

stuff stayed at 4½ inches. This type of internal
ballistics adversely affects all calibers right
down to the .22 rimfire.
Keeping your ammunition out of the sun and
sighting-in on an 80° F day for the time you
hunt at on a 25° F day will not affect accuracy or
your bullet impact much-it will some though.
At extended ranges both the internal ballistics
(cartridge and powder temperature and barrel
temperature) and external ballistics (air density,
etc.) will alter your hits more so but not much
until you get out to 500- to 600-plus yards and
this depends on the caliber-generally, real fast
flat shooting stuff is somewhat less affected.
The again, if you are hunting, why are you
shooting that far?
How do we get better results from our rifles?
Your gun should be well-maintained. Before
you go to the range make sure the bore is clean
and truly dry (more in a minute). Make sure
the moving parts are lubricated. Do what you
can to make sure the bolt's locking lug contact
points (all rifles have these) are greased to prevent any accuracy harming galling-in winter
conditions use oil. Lubing the locking lugs actually is very important-don't do it and you can
gall the contact surfaces and screw up the head
spacing some. Say goodbye to accuracy ...
At the range you may have to fire two or
more fouling rounds to remove any cleaning
solvent remaining in the bore at a microscopic
level. Passing a couple of dry patches through
after you solvent/oil clean your barrel will not
get the job done. A bore that is not truly free
of solvent or oil lubricates the fired bullet at
a microscopic level under pressure and can
cause fired bullets to impact at a different place
until the bore is fouled though firing-a good
time to use surplus or old ammunition. If you
are going hunting I would not clean the bore


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Table of Contents for the Digital Edition of Shooting Sports USA - January 2018

In This Issue
Shooting Sports USA - January 2018 - Cover1
Shooting Sports USA - January 2018 - Cover2
Shooting Sports USA - January 2018 - 3
Shooting Sports USA - January 2018 - 4
Shooting Sports USA - January 2018 - 5
Shooting Sports USA - January 2018 - In This Issue
Shooting Sports USA - January 2018 - 7
Shooting Sports USA - January 2018 - 8
Shooting Sports USA - January 2018 - 9
Shooting Sports USA - January 2018 - 10
Shooting Sports USA - January 2018 - 11
Shooting Sports USA - January 2018 - 12
Shooting Sports USA - January 2018 - 13
Shooting Sports USA - January 2018 - 14
Shooting Sports USA - January 2018 - 15
Shooting Sports USA - January 2018 - 16
Shooting Sports USA - January 2018 - 17
Shooting Sports USA - January 2018 - 18
Shooting Sports USA - January 2018 - 19
Shooting Sports USA - January 2018 - 20
Shooting Sports USA - January 2018 - 21
Shooting Sports USA - January 2018 - 22
Shooting Sports USA - January 2018 - 23
Shooting Sports USA - January 2018 - 24
Shooting Sports USA - January 2018 - 25
Shooting Sports USA - January 2018 - 26
Shooting Sports USA - January 2018 - 27
Shooting Sports USA - January 2018 - 28
Shooting Sports USA - January 2018 - 29
Shooting Sports USA - January 2018 - 30
Shooting Sports USA - January 2018 - 31
Shooting Sports USA - January 2018 - 32
Shooting Sports USA - January 2018 - 33
Shooting Sports USA - January 2018 - 34
Shooting Sports USA - January 2018 - 35
Shooting Sports USA - January 2018 - 36
Shooting Sports USA - January 2018 - 37
Shooting Sports USA - January 2018 - 38
Shooting Sports USA - January 2018 - 39
Shooting Sports USA - January 2018 - 40
Shooting Sports USA - January 2018 - 41
Shooting Sports USA - January 2018 - 42
Shooting Sports USA - January 2018 - 43
Shooting Sports USA - January 2018 - 44
Shooting Sports USA - January 2018 - 45
Shooting Sports USA - January 2018 - 46
Shooting Sports USA - January 2018 - 47
Shooting Sports USA - January 2018 - 48
Shooting Sports USA - January 2018 - 49
Shooting Sports USA - January 2018 - 50
Shooting Sports USA - January 2018 - 51
Shooting Sports USA - January 2018 - 52
Shooting Sports USA - January 2018 - 53
Shooting Sports USA - January 2018 - 54
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