Home of the RnR Design Adjustable Front Sight System
Sight Correction Factor
| This is a method of establishing the actual minutes of change for your
rear sight based on sight radius, the distance between your rear sight
aperture plane and the front sight aperture plane. The extra decimal
places are carried through for accuracy.
Mathematically one minute of angle at the distance of 100 yards equals 1.047197536 inches.
A standard Warner rear sight, our reference unit, has 40 pitch lead screws. This equals 0.025 inches of movement of the rear sight for each revolution of either the elevation or windage knob. This 0.025 of movement equates to 3 minutes of the sight aperture displacement, not at the target. By dividing the 0.025 of movement by 3, one minute would be worth 0.0083333333 inches of aperture displacement.
It is now a simple proportional problem.
One Min @ 3600 Inches (100 Yards) = One Min Rear Sight Movement
(1 Min @ 100 Yds) (1 Min @ Rear Sight)
___________ = _______________
3600 Inches X
(100 Yards) (Distance Between Sights)
X = _________________ = 28.64788903 Inches
The 28.64788903 Inches is the theoretical distance required between the front and rear sight aperture planes to obtain One Minute of precise movement at the target.
To calculate a correction factor for a specific set of sights, measure the distance between the two aperture planes. Determine this distance to within 1/8th of an inch. Divide this measurement by the 28.6479. The results will be your correction factor for your rifle.
Divide the 36.5 by 28.64788903, this equals 1.274 (rounded off). This
is your correction factor. Normally a 30 caliber 155 grain Sierra Palma
bullet traveling at 2950 fps needs 19.5 minutes of elevation to go from
600 yards to 1000 yards. Multiply the 19.5 minutes by the 1.274 correction
factor and you get 24.84 (again rounded off). This is the actual number
of minutes you need to move your sights for this particular rifle to
obtain a 1000 elevation.
All aluminum sight hardware and accessory items, except for the 30 mm lenses and
commercial bolts and washers,are designed and fabricated by RnR Design, Inc. No exceptions.
© Copyright RnR Design, Inc. 2008