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BillCA · October 27, 2008, 04:30 PM

Sight radius is the distance between the rear sight and front sight. The greater this distance, the easier it is to get a precise alignment of the sights. Of course a longer radius usually goes hand in hand with a longer barrel which can increase fatigue and make your arms unsteady too.

The longer barrel, essentially, gives you more precision because the further the front sight is from the rear, the smaller the fraction of a degree it moves per 1/10th inch of your input. Conversely, the shorter sight radius gun's has a gross scale of motion for every 1/10th inch. If in a 6" gun, that 1/10th inch movement translates to an offset of 1/2" at 25 yards, that same movement will translate to a larger offset from a short barreled gun - perhaps as much as 1-1/2 to 2".

You are moving the barrel thru an arc to align the sights. If you think of a Sextant or protractor with a 12" radius, the markings per degree are spaced further apart. This makes precision alignment easier by allowing you to read fractions of a degree (minutes). But if that Sextant or protractor has only a 2-inch radius, the degrees are crammed together and provide less precision.

Clear as mud?

October 27, 2008, 04:30 PM	#5
BillCA Senior Member Join Date: November 28, 2004 Location: Silicon Valley, Ca Posts: 7,117	Sight radius is the distance between the rear sight and front sight. The greater this distance, the easier it is to get a precise alignment of the sights. Of course a longer radius usually goes hand in hand with a longer barrel which can increase fatigue and make your arms unsteady too. The longer barrel, essentially, gives you more precision because the further the front sight is from the rear, the smaller the fraction of a degree it moves per 1/10th inch of your input. Conversely, the shorter sight radius gun's has a gross scale of motion for every 1/10th inch. If in a 6" gun, that 1/10th inch movement translates to an offset of 1/2" at 25 yards, that same movement will translate to a larger offset from a short barreled gun - perhaps as much as 1-1/2 to 2". You are moving the barrel thru an arc to align the sights. If you think of a Sextant or protractor with a 12" radius, the markings per degree are spaced further apart. This makes precision alignment easier by allowing you to read fractions of a degree (minutes). But if that Sextant or protractor has only a 2-inch radius, the degrees are crammed together and provide less precision. Clear as mud? __________________ BillCA in CA (Unfortunately)