I wouldnt mess with the rear sight. To lower the impact, I would get a higher base for the front sight.
Go to the Brownells website. They have the formula to figure how much you need to come up with the front sight to lower the impact you desire. Then buy a base accordingly.
Quote:
The distance from the borecenterline – shown running through A and C – to the line of sight
– shown at the tops of the sights  must be the same approximate distance or height at each sight
location. The rear sight has an adjustment range and you should use the middle of the range as your
starting point for measurements or to determine the correct sight for the rear sight.
Measure the barrel diameter at each sight location – shown at long arrows A and C in the illustration.
Divide each measurement by two to obtain the distance from borecenterline to top surface of barrel
at each location – represented by the short arrows at A and C in the illustration. Write down and label
your results.
Measure the height of the existing front sight. Add the height of the front sight to its corresponding
centerlinetotopofbarrel figure to obtain the distance between borecenterline and line of sight.
The distance between borecenterline and line of sight (just calculated at the front sight location)
minus the remaining borecenterlinetotopofbarrel distance (at the rear sight) will give the needed
rear sight height.
The basic principle is: B plus ½ A (short arrow) is the same total distance as D plus ½ C (short arrow)
OR ½ A + B AND ½ C + D BOTH EQUAL the distance from center line to line of sight.
To measure a rifle barrel for a missing rear sight involves taking three measurements to determine
the fourth measurement. In this example the fourth measurement is the rear sight height.
Barrel Dia. Measurement At Rear Sight .820”
.820” ÷ 2 = .410”
.410” is borecenterline to topofbarrel distance
8007410015
Determine Rifle Rear Sight Height
brownells.com
Barrel Dia. Measured At Front Sight .596
.596” ÷ 2 = .298”
.298” is borecenterline to topofbarrel distance
Barrel Diagram Example With Numbers
brownells.com 8007410015
Measure the height of the existing front sight.
Add the height of the front sight to its corresponding
borecenterline to topofbarrel figure
to obtain the distance between borecenterline
and line of sight.
Measure .503”
.298” + .503” = .801”
.801 is the borecenterline to lineofsight distance
One half barrel diameter at front sight plus front sight height will give height of sight line above borecenter
line. Height of sight line above borecenterline minus one half barrel diameter at rear sight
will give rear sight height
OR
Use the formula for determining rear sight height in this example:
Need to find Rear Sight Height at B (½ C) + D – (½ A) = B
Plug in the words and numbers (½ x .596) + .503 – (½ x .820) = Rear Sight Height
Do the math (.298) + .503 – (.410) = .391 Rear Sight Height
