What is mechanical zero?

[garrettwc]

And how is it used?

I was reading a discussion on sighting in a rifle, and it said when using iron sights you should find the mechanical zero for the rifle and use that as a starting point.

What are they talking about?

I'm a total newb to long arms.

 

[BigG]

Put both sights, if movable, in the center position of their adjustment.

 

[Carlos Cabeza]

I'm thinkin' mechanical zero refers to scope adjustment. Try this link and see if it can help explain.

http://www.snipercountry.com/Articles/MechanicalZero.asp

 

[garrettwc]

Thanks BigG, that's sort of what I thought.

If I have the mechanical zero set as you described and I am hitting where I aim is that saying the same as fixed sights on handguns POA=POI for that particular rifle and that is was "built right" from the factory. If you are way off with mechanical zero, is that a sign the sights weren't installed correctly?

Carlos, I was talking iron sights, but that article is very good. Going to have to print that out for my files. Thanks.

 

[Carlos Cabeza]

You're welcome. I thought you may have just "heard the term" and were looking for a solid definition. I have a Winchester 9422 .22 mag with iron sights that is dead on at 100 yd but the rear sight is noticeably left of center. I'm thinking it may be poorly assembled but have not wanted to mess with it since it shoots OK.

 

[garrettwc]

The worst part about learning a new skill is now I want to go try it and I'm stuck at work.

 

[JohnBT]

Quit.

John

 

[garrettwc]

 

[Mal H]

... and I'm stuck at work.

Don't let that stop you! (Err, that is unless you work at the Post Office. )

 

[garrettwc]

Don't let that stop you! (Err, that is unless you work at the Post Office)

Now that you mention it, the pile of dirt from the warehouse foundation they dug next door would make a nice berm.

 

[goalie]

For iron sights, take the windage knob and turn it all the way that it will go in one direction, let's say to the left for this example. Now, count the clicks as you turn it to the right as far as it will go. Now you know how much windage you have (how many clicks) of adjustment on the rifle's sights. To get to mechanical zero, count clicks as you go back to the left and stop when you reach one-half as many clicks as it took to go all the way over from left to right. Your windage is now at mechanical zero, and you can even mark it with a grease pencil or something if you want to make changes from mechanical zero easier later on.

Repeat with elevation, substituting up and down for left and right.

 

[BigG]

Gee Goalie, is it cheating if I just line up the witness marks?

Most iron sights have crude windage and elevation adjustments, i.e., drive rear sight over in its dovetail for windage, or, front sight if it is dovetailed - a lot are not. The elevation usually has a ramp or stairstep type adjustment. If the rear sight has knobs, it is usually way more expensive than most mfrs want to put into fixed sights. They even leave sights off of most models today.

Rear sights move in direction bullet is to strike. Front sight, in opposite direction to intended bullet strike.

 

[goalie]

Sorry, I am used to match sights on rifles. What I posted would work great on an AR type rifle or anything else with click-adjustment knobs for windage and elevation.