I do agree the load makes a difference.I have actually done range sessions to "sight in" fixed sight Colt SAA clones by trying different bullets and powderswith success.
I have no doubt the formulas given work.I lose them,forget them,etc.
For myself,what works is understanding the principle.
The geometry is proportional.The bullet error from point of aim and the distance to the target are the two legs of a triangle.The rise and the run.
The sight correction and the sight radius are a scaled down version of the same triangle.The rise and run ratio are the same.
What we need to know is the distance to the target using "sight radius" as the unit of measure.If the target is 100 "sight radii" away,sight changes will be multiplied by a factor of 100.
Likewise,if you are at 7 yds (7 x 36 in)=252 in Suppose we have a 6 in sight radius.We are now in the common unit of inches,and 6 divides into 252 =42 times.So,at 7 yds,the target is 42 sight radii away,therefore a sight correction will be multiplied 42 times on target.
That means .010 in off the sight would be .420 at the target..050 off the sight would be 42 x .05 or 2.1 in on the target.
So,remember,once you convert to a common unit,you determine the number of sight radius to the target,and that is the "factor".Sight corrections will be multiplied that much,or,the correction on the target can be divided by that factor for the correction at he sight.
For myself,I can always remember that and apply it to any range or sight radius.
I have no doubt the formulas given work.I lose them,forget them,etc.
For myself,what works is understanding the principle.
The geometry is proportional.The bullet error from point of aim and the distance to the target are the two legs of a triangle.The rise and the run.
The sight correction and the sight radius are a scaled down version of the same triangle.The rise and run ratio are the same.
What we need to know is the distance to the target using "sight radius" as the unit of measure.If the target is 100 "sight radii" away,sight changes will be multiplied by a factor of 100.
Likewise,if you are at 7 yds (7 x 36 in)=252 in Suppose we have a 6 in sight radius.We are now in the common unit of inches,and 6 divides into 252 =42 times.So,at 7 yds,the target is 42 sight radii away,therefore a sight correction will be multiplied 42 times on target.
That means .010 in off the sight would be .420 at the target..050 off the sight would be 42 x .05 or 2.1 in on the target.
So,remember,once you convert to a common unit,you determine the number of sight radius to the target,and that is the "factor".Sight corrections will be multiplied that much,or,the correction on the target can be divided by that factor for the correction at he sight.
For myself,I can always remember that and apply it to any range or sight radius.