AR paralax adjustment


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mljdeckard
April 5, 2008, 06:53 PM
This is something I should probably know, but I never got around to figuring it out.

If the aiming system (sights, scope, red dot, etc.) on an AR-style rifle sit about two inches above the barrel, and you have to do a close in precision shot, what is the best way to adjust it? Just aim two inches high?

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taliv
April 5, 2008, 06:55 PM
yep, or two and a half

rcmodel
April 5, 2008, 06:56 PM
Yep!

Do anything else, and whatever the problem was you needed to shoot, has already gone and done what you needed to prevent.

Shoot it on paper at all ranges.
Then Learn the Trajectory at all ranges, and commit it to memory.

(Or tape a cheat-sheet on the side of the scope.)

rcmodel

mljdeckard
April 5, 2008, 07:15 PM
There's no such thing as a push-button adjustment system or anything?

trinydex
April 5, 2008, 07:17 PM
at what distance does this two inch higher begin to take affect?

mljdeckard
April 5, 2008, 07:38 PM
Your sights are two inches higher than the point of release for the bullet. They are set this way so that it is possible to aim more comfortably than raising the barrel to the level of your eye. This in turn makes it possible to align the barrel, chamber, bolt, carrier, and buffer tube to put the recoil into a straight line, both allowing the buffer tube system and putting the recoil straight back, rather than an angle which always lifts the muzzle, like most rifles which raise the barrel higher.

This means that out of the barrel, the point of impact is 2-2 1/2 inches UNDER the point of aim. As for when this difference levels out, it depends on where you zero your rifle. In the army, we click the rear sight one click in elevation at the 25 meter zero range to compensate, and them click it back for the full distance range.

But there is no set process taught to compensate, say, if you are aiming for a person's eye at a range of less than ten meters.

rcmodel
April 5, 2008, 09:14 PM
All open sights, scopes, red-dots, whatever, are always higher then the bore of any rifle.

The barrel points up slightly in relation to the sights to compensate for drop at long range.

The bullet first crosses the line of sight at close range, raises above it at mid-range, then falls back down to hit at the range the rifle is zeroed for.

Beyond that point, the bullet continues to drop and will never be above the line of sight again.

SO, the bullet crosses the line of sight twice, once at close range, and again just beyond the distance the rifle is zeroed at.

You can download free ballistics software here:
http://www.remington.com/products/ammunition/ballistics/remington_shoot_ballistics_software.asp

Select the load, plug in the sight height & zero range, and it will tell you where the bullet path is going to be at any other range.

rcmodel

rangerruck
April 5, 2008, 09:38 PM
at 25 yards or less, just move your aim.

trinydex
April 5, 2008, 09:47 PM
or just practice enough that you know eh?

mljdeckard
July 14, 2008, 10:32 PM
Is THIS a viable solution? (Scroll down to the CSAT rifle sight.)

http://www.xssights.com/store/tactical.html#CSAT

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