Now, I'm not the biggest rifle user. But I have a bushmaster I'm fond of, and I'm trying to get at some better shooting. I know that on an ar 15 for mid chest hits at 25 yards its like a 4 inch drop right? So how do you prep that aim on a new out the box RDS? Say your using the standard 10 marked, do you aim at six with the sight to get the correct placement?

25 what? 25'? 25yrds? 4" drop for what caliber? What gr. weight? What barrel length and twist rate? (I see you have added some info).

I can't imagine any standard AR-15 caliber that experiences a 4" bullet drop in 25 yrds. If you are asking about adjusting your point of aim to shoot at a close range target it depends on what distance your RDS is zeroed at.

If you are asking about sighting in a new RDS:

- Verify your BUIS zero, if so equipped.

- If iron equipped decide whether you want a co-witness or 1/3 sight picture and select the optic and mount combo that get you there.

- Sight in RDS at the distance that makes the most sense for your specific uses for the ammo you plan on using and zero to that.

quote:

Say your using the standard 10 marked, do you aim at six with the sight to get the correct placement?

I have no idea what that refers to, but at close distances with a 223/5.56 AR, the point of impact will depend mostly on the zero distance and the height of the sight over the bore line. The trajectories of different ammunition at such a close range like 25 yards don’t make much difference.

As an example, I usually zero my ARs at 50 yards, and the centerline of an Aimpoint sight is about 2.9 inches above the center of the barrel. If I’m engaging a target at 25 yards, I need to aim about 1.2 inches high to hit my desired point of impact. That’s not, however, because the bullet is already dropping below the line of sight at that distance; it’s actually rising toward where it would intersect the line of sight at 50 yards. As the distance increases toward 50 yards, the difference between the bullet path and line of sight decreases, and the opposite is true at shorter ranges. At 15 yards I’d have to aim ~1.7 inches high and at 7 yards the offset would be ~2.4 inches high because the bullet is still rising, and those distances are how far below the line of sight the bullet is.

Different sight heights and zeros would change those line of sight/point of impact distances. They can be determined by actually shooting at different ranges (best method) or by using a ballistics calculator.

With a new sight, the best procedure is to mount it on the gun, decide what distance you want to zero the rifle and sight at (I like 50 yards for a 223/5.56 AR), go to the range and zero there, then shoot groups at closer and farther distances than 50 yards to see where you hit and how much you must adjust your point of aim to hit at those distances. If, for example, at 100 yards your groups are 2.5 inches high, then obviously that’s how much you must aim low to hit the 100 yard target. When you get much beyond 50 yards, then differences in ammunition and bullet trajectories begin to matter for precise results, and you must test the specific ammunition you’ll be shooting there.

This all depends on your zero, if you are shooting a closer distance than your zero, then you need to hold higher. For example if you are zeroed at 50 yards then you would hold about 2" high at 25 yards to achieve poi.Zero your irons then zero your red dot, just remember if you are closer than your zero you have to hold higher on the target to achieve the desired placement. If you want to have a defensive zero pick either 25, 50, or 100 yards respectively.