Tuesday, December 15, 2015

Zero Like A Hero Pt 2: How It All Works

Last week, we talked about why zero is important, and the math and theory involved in zeroing a rifle. This week, we'll look at the hardware side of the process.

All optics have a couple things in common: a glass lens, a method for secure attachment to a rifle, an aiming point (called a reticle), and a mechanism for adjusting the point of aim. The specifics vary a bit between the types of optics, but the parts will be there. These parts all work together in a pretty precise system, so any rough handling or impact calls for a check and possible re-zero.

Types of Optics
This is an electronic "holographic" optic (also known as a red dot sight):
Sightmark Ultra Shot Reflex Sight
  • The mounting hardware is built into the bottom of the optic body. 
  • The lens is in the shroud at the right side. 
  • The adjustments on this optic require a hex key in the holes on the top and left faces, as indicated by the arrow markings. 
  • The reticle is electronically projected onto the lens, and many of these optics offer multiple reticle options, so that the shooter can select an aiming point that fits their personal taste. 
  • The large knob near the lens adjusts the brightness, allowing the optic to work in a wide array of lighting conditions. 
Holographic sights are quicker and more intuitive than a traditional magnified scope, but they have little to no magnification built in. There are magnifiers that can pair with them, but magnification remains fairly low.

One concern with an electronic optic is the requirement for battery power. With most of these optics, "no power" means "no reticle". This may or may not be a dealbreaker for you; in my home, it's just a factor that requires awareness and planning.

This is a traditional scope, albeit a rather large one:
Cabela's Outfitter Series 1" Scope
  • The drums just to the left of center are called the turrets, and are the mechanism for adjusting the point of aim. 
  • There are two lenses in this type of optic, with one mounted at each end. 
  • The two bands near the turrets are referred to as rings, and are the method for mounting the scope to a gun. 
  • The reticle is etched onto the glass, and is seen clearly when the eye is brought in line with the optic.
Turrets with caps removed.
When the caps are removed from the turrets, the adjustment mechanism is revealed. Turning the knobs moves the point of aim in the indicated direction. The distance the point of aim moves is indicated on the knob. For this particular scope (and a great number of scopes out there), one click of the knob moves the point of impact 1/4" at 100 yards. This translates to 1/2" at 200 yards, 3/4" at 300 yards, and so forth.

Now that we know how the mechanisms work, let's make it do something useful.

How To Zero
  1. As mentioned last week, start your zeroing at 25 yards. 
  2. Set your rifle in the most stable support available; this dramatically reduces the effects of shooter error in the zeroing process. 
  3. A large target can be beneficial in this part of the process, on the off chance your optic and your rifle are more significantly out of alignment. 
  4. Line your scope up with the bulls-eye, and fire three to five shots, taking whatever time you need to line up between shots. These shots need to be grouped fairly close together. If they are not, fire another three to five shots and see if they form a close group.
    Three shots in a tight group and a flyer to the left. 
  5. If your shots can't form a close grouping, there is a problem with either your gun, your optic, or your shooting technique. Most of these problems are fairly simple to correct, when you know what you're looking for. We'll troubleshoot these problems next week.
  6. Once you are able to cluster your shots together, it's time to adjust your optic. Where one click moves 1/4" at 100 yards, it takes 4 clicks to do the same at 25 yards. 
  7. Turn the scope knobs in the necessary direction to align your point of aim (where you want it to hit) and point of impact (where it actually hits). 
  8. If your bullets hit right of your point of aim, turn the knob on the side of the scope in the direction marked "right" the appropriate number of clicks. If your bullets hit low, turn the top knob in the direction marked "up." Do the opposite if your bullets hit high or left.
  9. Once you've made your adjustments, fire another set of shots, and see how close your adjustments have gotten you to the bulls-eye. 
  10. If more adjustment is needed, repeat the process until your shots group on the bulls-eye. You're then ready to move to 100 or 200 yards.
  11. This portion of the process should be fairly quick, as you're now fine-tuning your zero, and should be fairly close to start. If you're confirming zero at 100 yards, you'll want to be about 2" high, as we said last week. At 200 yards, you should be dead-on. 
  12. After this is done, you can do your periodic checks at 100 or 200 yards, and skip the 25 yard portion.

Next week, we'll look at the reasons your rifle may not zero readily, and ways to correct the problem.


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