Zeroing in a reflector sight

[Alexey931]

Hi,

This question has certainly been already answered; unfortunately, I don't have the command of the necessary terms. Sorry.

I'm talking the sighting of an ordinary combat weapon here.

Dealing with a sighted firearm, you deal with the mismatch between the barrel axis and the sight axis (parallax; is it called so on the firing range?). The flying bullet crosses the sight axis twice. This is the blank, or point blank, range. For M16, IIRC, it's something like 25yd on the ascent, and 700yd on the descent. So you can put up your test target at an easy and convenient distance of 25yd, and know the bullet drops there again at 700yd. That's according to the guidelines from the Manual, which become totally irrelevant as soon as you try and mount a sight with the different parallax.

Of course, this problem is nonexistent with the weapons like L85 or Tavor, which never enjoyed the iron sights.

How am I supposed to cope with the reflector sight on a "non-native" gun? I'm not talking about fixed ranges, as in sports shooting. I'm talking about making the gun useful on the battlefield, within its sighting range.

 

[imashooter]

A reflector sight as in a "reflex" style sight? If so a ballistics calculator can be a big help. There are many free ones online. Using a ballistics calculator, you will typically enter data such as the ballistics coefficient of the particular ammunition, its muzzle velocity, the center of the optic height above the center bore of the barrel, for example 2.5", (i guess you use metric), bullet weight. There's other data you can enter if available but those I listed will be very helpful. Barrel length can be a factor when considering the muzzle / initial velocity, however, the numbers given out by ammunition companies are fairly generic but do work ok for most of us who don't do long range precision shooting, sniper, etc. Does this answer your question?

 

[Alexey931]

Almost perfect, thanks! "Ballistics calculator" means many things; what are the specific keywords besides the "optic height"?

 

[imashooter]

Almost perfect, thanks! "Ballistics calculator" means many things; what are the specific keywords besides the "optic height"?

This particular one, and most others I believe, uses the term "Sight Height".

http://www.shooterscalculator.com/ballistic-trajectory-chart.php

 

[imashooter]

If you need help with this, let us know.

 

[Alexey931]

Thanks!

 

[GarySTL]

I'll add that "parallax" normally refers to the condition where when using a scope the intermediate image and the reticle are not in the same plane. When you move your eye behind the scope the cross hairs appear to move on the target even though the rifle is not moving. This results in different impact points on the target.

Here's a more complete explanation. Most red dot sights exhibit little parallax, but it varies.

 

[Everready73]

If you are sittings see ar15 you could also go with an optic with a bullet drop compensator (bdc) . Primary arms ACSS reticle is the best it there I'm. They have several options. 1x6/8, 2.5x 3x and 5x prism sites, and are coming out with a new 1x prism that is closest to a red dot next month. Otherwise a ballistics calculator and knowing your holds works with a red dot. I believe if you zero at 50 yards you are 3 inches high at 100 and on again around 250.

The height of the optic off the bore doesn't make much difference once you establish your zero