Why is it that a longer sight radius is beneficial to accuracy, or at least linked to a perception of more being accurate?

Thanks.

The greater the distance between the front and rear sights, the easier it is to see slight misalignments between the two when trying to line them up.

Imagine the front and rear sights only an inch apart. Then imagine a normal sight setup. Which seems more accurate to you? That is merely a more extreme example.

It's obvious there is something to it, as most of the competition guns have that extra long extension on the barrel, and the sights are very far apart....truth be told, if the front post is on target and you have good form does it real make a huge difference to the average shooter how far the sights are apart?

Or would this only really matter to someone like Tubb?

It isn't going to make much of a, if any difference for MOST shooters.

It's geometry. Try this to see why, as Troy stated, you can aim more PRECISELY with a longer sight radius:

Point your two index fingers up. Place them about three inches apart and sight down on them like they were front and rear sights. Move your front sight (finger) side-to-side about one half inch and see how far this moves your point of aim on the wall across the room. Now hold your front sight (finger) as far away from the rear as you can and move it side-to-side the same half inch. You will note the distace that your point of aim shifted is MUCH smaller with the longer sight radius.

Since no one can hold a gun absolutely still, the longer sight radius results in less AIMING error. Even for David Tubb.

I cant group with a 16" sight radius like I can with the 20" radius.

The closer the front sight pin is to you, the more work it takes to keep the pin centered in the peep.  Its geometry like PAEBR332 said, or you can think of it in terms of leverage.  

Maybe this will help. I will use only round numbers because this is just to demonstrate the application, not the accuracy of it.

1 MOA(minute of angle) = 1/60 of a degree if I remember my conversions correctly = 1 inch at a distance of 100 yds

A 6" sight radius that is moved 1 inch to the right or left rotates through the arc of a circle approx 10 degrees. At 100 yds this equates to approx. 600 inches of movement.

A 20" sight radius that is moved 1 inch to the right or left rotates through the arc of a circle approx. 3 degrees. At 100 yds this equates to approx 180 inches of movement.

As you can see, any movement of the shorter sight radius has a 3x greater affect on the point of impact than the same movement of a longer sight radius. Thus, by minimizing the affect of sight movement the shooter becomes more accurate.

Don't know why, but this made more sense to me, when applied in conjunction with the above.

Thanks guys, I get it now. [BD]