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Posted: 7/19/2003 2:32:31 PM EDT
how do i zero my ar-15? i dont understand the one on the site that well :( i want to zero it at 25 meters. thanks.
Link Posted: 7/19/2003 2:48:20 PM EDT
[Last Edit: 7/19/2003 2:54:07 PM EDT by Big-Bore]
Bullets travel in a curve, you know that already. The bullet leaves the muzzle below the line of sight, crosses the line of sight to be above it, and then crosses it again down range. Often a zero of 100 to 150 yards will also give a close in zero of 25 yards. Given the AR's high position of its sights above the bore center line (2.5 inches), a standard military M193 load of a 55 gr. bullet at 3250 fps, you will have to sight in at a pretty long range. With the bullet sighted with a 150 yard zero, at 25 yards the bullet will be 1.5 inches below aim. It does not cross the line of sight the first time until 75 yards. To achieve a 25 yard first line of sight crossing, the rifle would have to have its second zero at 375 yards. So, if you crank your rear sight up to around 375 yards, you should be able to adjust your front sight enough to zero at 25 yards. That is putting a very steep arc to the bullet. With a 25 yard zero, at 50 yards the bullet is +2.23, at 75 yards, +4.24, 100 yards + 6, 125 +7.45, 150 +8.61, 175 +9.43, 200 +9.89, 225 +9.96 and finally at 250 the bullet starts back down being +9.59 at that range. At 300 the bullet is 7.44 high, 350 +3.1, and finally a second zero at 375 yards. There are the figures. For a different bullet weight the trajectory is not all that much altered, but you have a starting point now to get your 25 yard zero. As I said, set your rear sight to as close as possible to 375, then tinker with the front. Good luck.
Link Posted: 7/19/2003 3:01:54 PM EDT
[url]http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw[/url] Another great site for the AR community.
Link Posted: 7/19/2003 3:03:52 PM EDT
thanks guys- i got it now
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