Monday, October 18, 2010

How to zero a rifle

I have seen far too many people who go to the range to sight in a rifle, and leave a couple hours later no closer than when they started. So I am putting this together as a reference point.

What you need:
- a rifle
- sights (iron or scope)
- a rest of some sort to put the rifle on.
- instructions to sights, if needed.
- 20 rounds of ammo. Use the same type of ammo for all shots. Use the same type as you plan to hunt / shoot with.

Make sure:
The sights are firmly secured to the rifle, according to manufacturer's specifications.
If the sights move or wiggle, then you will not be able to sight in.

Adjusting sights:
Most scopes and iron sights are adjustable. You need to know how to adjust your specific sights, so read and use the instruction manual. I will give general tips - based on common adjustments. Naturally, your sighting system may have variances, so again, please consult its instruction manual.
Windage - Adjustments to the left and right
Elevation - Adjustments up and down
MOA - "Minute of angle" - it is a measurement. 1MOA is approximately 1 inch at 100 yards. 
POI = Point of impact
POA = Point of Aim
Sighting in is the act of making the sights' POA = POI at a given range. In other words, "where ya aim is where the bullet impacts."
Most sights adjust in either whole MOA increments, or common fractions thereof (1/2, 1/4, 1/8)

Most sighting systems have adjustments relative to the POI (point of impact). Meaning, suppose your sight says a turn of 1 click clockwise = 1 MOA adjustment to the right; then 1 click will shift the point of impact of the bullet 1 MOA to the right.



Step 0

Yes, I meant "Step 0" - as in, a preliminary step.

If you have a laser bore-sight, use it. Turn it on and install into the bore. Inside your home, put the laser about 15 yards away, or closer. Move your sights to be about 1" - 2" high at that range - meaning your crosshairs are above the laser by an inch or two.

If no laser boresight, do this: Put your rifle (unloaded, of course) on the rest in your house. Aim at the far wall. Look down the bore, and move the rifle to a rested position where a specific object on the far wall is appearing in the center of the bore. Move your sights until the crosshairs are 1" to 2" above the object.


Step 1

At the range, at 15 yards, put up a large target.
Aim dead-center.
Fire once.
Observe where the bullet impacts.

If you cannot see where the bullet impact is, take one of two actions:
1. Use a larger target.
OR
2. Shoot at the corners - slow fire.
Check for impact at each corner of the target after each shot. When you see the impact, you know where the gun is shooting.

If your bullet is, say 2" low f the bullseye and 1" to the right, make the adjustments.
Remember, most sighting systems have indicators on which way the adjustment moves the POI. In this example, I would adjust the sights 1" to the left (usually counter-clockwise). I would either leave the elevation alone (if my sights were 2" above the bore), or adjust 1" up (if sights were about 1" above bore).

Make the POI = the POA - where ya aim is where it hits. 


Step 2

Repeat Step 1 at distances of 25 yards, and/or 50 yards.
Do the same at the desired range you want to establish a zero.


Note: 
Instead of firing a single shot, some folks use a 3 or 5 shot group. That is fine, too.


Some conversions:
1 MOA:
1" at 100 yards
2" at 200 yards (etc.)
0.25" at 25 yards
0.50" at 50 yards

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