CALCULATING AND MAKING SIGHT CORRECTIONS.

When using iron sights making corrections for either windage (left and right) or elevation (up and down) is not always a straight forward affair.  When drifting a front sight blade how far do we move it in which direction for ‘X’ change on the target?  Likewise for the elevation; how much adjustment is required to the height of the rear sight move a bullet point of impact at ‘Y’ range?

To begin with let us first determine how moving the front and rear sights translates to where our bullets will land on the target:

Front sight – move in opposite direction to the adjustment required at the target.  If shots are too far left of the aiming point the correction required is to move the fall of shot to the right.  To do so move the front sight left.  Bullets landing low of the point of aim need to be raised and reducing the height of the front sight will achieve this.  It’s all a lot steering into the skid when your car slips in snow or ice.

Rear sight – move in the direction the fall of shot needs to go.  When bullets are left of point of aim (POA) move the rear sight right.  If shots are landing low on the target raise the rear sight.

Now we have established what bits need to move in which direction the next step is to calculate the amount of movement that is required to correct the error.

Formula

Amount of Error X Sight Radius
= Sight Correction Needed
Distance to Target

Example
At 100 yards (3600 inches), your shot is 6″ low and the distance between your front and rear sight is 19.5″.

6 X 19.5
= .0325
3600

Since you are shooting low, you would need to lower your front sight by .032″.

It’s that simple BUT the good folks at Brownells have made it really easy for us all with the aid of this handy little SWF:

Keep your powder dry.

Jeff

 

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About JeffinNZ

Dedicated cast bullet shooter, runner, fisherman and father for two beautiful girls.
This entry was posted in Ballistics, General, Rifles. Bookmark the permalink.

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