From: bartb@hpfcla.fc.hp.com (Bart Bobbit)
Newsgroups: rec.guns
Subject: Re: Garand Sight Markings
Date: 5 Jan 1995 11:56:53 -0500

On M1 rear sights, the elevation knob is marked in hundreds of yards.
The `2' means 200 yards, the 6 is for 600 yards and so on.  Each click
is worth one MOA.

The windage marks on the receiver are worth 4 MOA per mark.  Each
click is worth one MOA.

Here's how you `zero' the rear sight:

  1.  Turn the windage knob until the vertical line on the sight
      base centers on the middle line on the receiver.  The sight is
      now at mechanical windage zero.

  2.  Turn the elevation knob counter clockwise until it bottoms.
      Then raise it about 8 clicks.

  3.  Shoot the rifle at 200 yards.  

      a.  Adjust windage by loosening the front sight with a 3/16ths
	  inch hex wrench, then move it opposite the direction you
	  want the group to move; don't forget to tighten it down.
	  You may have to make several adjustments to get it right.

      b.  Adjust elevation by turning the knob.

      c.  Be sure you have a good sight setting to center your group
	  on the target.

  4.  Without moving the elevation slide that has the aperture in it,
      loosen the screw in the elevation knob, then move the elevation
      knob until the `2' aligns with the mark on the sight.  Then
      tighten the elevation knob screw.

This should `zero' the sight.  You can now set the elevation knob to
what ever range you'll shoot at and be real close.  

BB

From: bartb@hpfcla.fc.hp.com (Bart Bobbit)
Newsgroups: rec.guns
Subject: Re: National Match sights for Garand
Date: 9 Oct 1994 16:09:25 -0400

Larry Schuette (schuette@ait.nrl.navy.mil) wrote:

: What does the Globe front site buy me?  

That globe front sight lets you use apertures on the front end.  Apertures
are easier to align on the target.  But aperture front sights are not
allowed on service rifles in matches for service rifles, such as DCM
matches.  But in NRA matches, they are legal and the rifle is then
considered a match rifle.  The highpower rule book explains the differences.

: Beside the apeture size, and the MOA per click difference
: what does the NM sight buy you? 

NM sights have their parts fit to closer tolerances.  Which means the
aperture won't bounce around from shot to shot and be in a different
position.  I've seen a lot of commercial NM rear sights for 30 caliber
service rifles and they are so sloppily fit, they've got 2 to 3 MOA
of looseness in them.  Which means even if the rifle is a tackdriver,
it can't be shot accurately because the rear sight doesn't stay in
the same place for each shot.  A 1/2-MOA change on an NM rear sight
changes its position about .0039-in.  If the elevation slide is loose
enough, the aperture in it will have several thousandths of an inch
slop and the 1-click change won't be noticed.  

Good NM rear sights have their base and elevation slide lapped to a
virtual zero-tolerance fit.  And the lock in the windage knob is set
to the correct tension, too.  These sights should be checked with a
dial indicator on the rifle for repeatability.  If they have more
slop than 25% of each click, they need fixed.

It's much like shooting a rifle with a scope.  If the scope is loose
in its mount, or the mount is loose, the rifle won't shoot accurately
because the line of sight relative to the barrel is not the same for
each shot.  Hold the aperture of a standard service sight and move it
around.  You can see it move and stay in position several thousandths
of an inch from where it was.  

: Can I just buy the smaller appeture and
: stick it in my normal rear sight 

Not if you want good, repeatable sights.  Although the smaller 
NM aperture will give a better sight picture, the normal slop in
the service sight will still be there. 

NM rear sight apertures rotate in the elevation slide.  The hole
in them is offset from their axis by about .002-in.  They have two
ball detents in them that fit in a groove in the elevation slide's
ring.  A notch at the back of the hood indicates the position of the
aperture.  If the notch is up, that means the aperture is at the top.
Rotating the hood 180 degrees to put the notch down relocates the
off-center aperture about .004-in. lower causing the effective sight
axis to go down 1/2 MOA.  The elevation knob still moves the hood
1 MOA per click.  So, you have 1/2 MOA adjustments in elevation by
rotating the hood to notch-up or notch-down.  

Some folks have drilled out their service sight's elevation slide,
then grooved it to hold the NM aperture which is held in place by a
C-ring and washer on the slide hole's front end.  But that's hard
to do a good job of because the slide metal is do darned hard.

BB