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Old January 27, 2013, 02:18 AM   #1
DavidB2
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Sight adjustment on M1 Garand?

My M1 is shooting slightly to the left. I just wanted to confirm that I should turn the windage dial to the left in order to get the rifle to be on target? Thanks.
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Old January 27, 2013, 02:21 AM   #2
golfnutrlv
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The Garand sight works like a modern scope. Turn the direction you want the impact to move. In your case, click to the right.
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Old January 27, 2013, 07:26 AM   #3
kraigwy
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Quote:
The Garand sight works like a modern scope
Or any other rifle, pistol or revolver. Always move the rear sight to the direction you want to move the bullet impact.
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Old January 27, 2013, 09:24 AM   #4
4EVERM-14
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Move the rear sight 'In the direction of the Correction'
On the M1 and M14 a way to remember how to move the bullet impact to the right is to turn the windage knob with the right hand so the thumb goes vertically. "Thumbs Up Right"
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Old January 27, 2013, 04:32 PM   #5
P5 Guy
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Front Sight

Is the front sight centered on the gas cylinder? If not a 3/16th inch Allen key is needed to loosen this and move the front sight to chase the Point of Impact.
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Old January 27, 2013, 04:32 PM   #6
stepmac
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Here is the SIGHT ADJUSTMENT RULE:

Move the rear sight in the direction you want the bullet to move.

Move the front sight in the opposite direction you want the bullet to move.

So, when adjusting the rear sight, if you want the bullet to go left turn the sight adjustment so that the rear sight moves left.

If, however you are shooting a rifle (or pistol) that drifts the front sight to adjust bullet impact and you want the bullet to move to the left you drift the front sight TO THE RIGHT.

So windage adustment using the rear or front sights are opposite from one another.

Same goes for elevation. If you want the bullet to rise, move the rear sight up. If you are adjusting your front sight; if you want the bullet to go up you file down the front sight.

Got that? You have to think about it, because it's easy to forget.

Concerning elevation: The relationship between line of sight and bullet tragectory is something you have to study, because when the bullet leaves the muzzle it is below the line of sight, then it rises to cross the line of sight, then it falls back down to it and then keeps going below.

So, The bullet will cross the line of sight twice. Once going up and the other coming down. Therefore the rifle will appear to be perfectly sighted in at two places, one close and the other far. Reloading manuals will help you with this trajectory stuff.

One more thing. There is something called "drift". The bullet's flight is affected by the spin of the bullet. This has a measurable affect in large caliber guns and slower moving bullets, like the old 45/70 and artillery rounds. It affects small fast bullets too, but since they are in the air less time it is not so noticeable.

Look at an old Trapdoor Springfield Buffington rear sight. You will note that as the rear sight is elevated it also moves to the left. Why? Compensation for drift, of course. The bullet, due to drift moves right. Since we move the rear sight the same direction we want the bullet to move, the rear sight angles left as it rises. The farther the bullet flys the more time drift has to move the bullet, so the affect of drift increases with range and so does the rear sight move farther left as it rises. The rear sight on an Artillery Luger is similar. I think that the 1898 Krag's rear sight has drift compensation too. Drift is significant, I'm told, when firing artillery rounds which makes sense. Unless you are a target shooting you don't need to worry about drift.

Today artillery fire is computerized. It used to be a slip stick computation. They even compensate for the turning of the Earth while the round is on it's way down range. Artillery rounds also go very high. The extreme heigth of an arty round is called it's Max Ord. It is something like 30,000' (I can't recall). Saddam Hussein was making a cannon that could shoot into space and hit Israel! The barrel was planted underground and bolted together like pieces of pipe.

I'll bet there are some arty guys here who know a lot more about cannon fire than I do. It is an interesting science.
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Old January 27, 2013, 05:24 PM   #7
kraigwy
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If one has to ask which way to turn the sights, I do believe Spin Drift and the Coruikus Effect should be put off for a while.

If you want it, but don't want to learn the fomula then just down load the "Shooter" program on your Ipod/Iphone/Ipad.

You plug in the numbers into the program, then highlight the range and it will give you the corrections.

Beats taking a slide rule to the field.
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Old January 28, 2013, 07:46 AM   #8
Bart B.
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Some interesting things mentioned in this thread.

Spin drift of the .30-06 round's about 7 inches at 1000 yards; this has been known since the 1930's. Not enough to ever be noticed unless you can shoot your Garand no worse than 1/4 MOA at that range. Besides if you have it zeroed at 600 yards, the bullet's never gonna be more than about 1/4 MOA sideways from the line of sight. Best thing to do is forget about spin drift. No high power rifle shooter I know of that wins the matches and sets the records ever worried about coriolis or spin drift; maybe 1 out of 1000 would always put their first shot at 1000 yards within 5 inches of point of aim anyway, but I never met him. . . .do you get the drift of this?

Best place for the front sight, windage wise, is what lets you get a zero with the rear sight on mechanical zero. That way, you've got maximum windage either side of the sight's windage range, plus, it's easy to remember where windage zero's at on the sight. Do this by first setting your rear sight to zero; index line centered on the middle hash mark. Then shoot a few rounds at 100 yards. Note where they group relative to your line of sight. Then move the front sight about .008" sideways for each MOA you need to correct for; in the opposite direction you want to move the group center. Note the marks on the receiver are .03125 inch apart; that's 4 MOA. Shoot another group; make changes if necessary. Who really cares if the front sight's 1/16th inch off the center of the gas cylinder, anyway?
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Last edited by Bart B.; January 28, 2013 at 08:13 AM.
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Old January 28, 2013, 08:43 AM   #9
kraigwy
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Quote:
Spin drift of the .30-06 rounds about 7 inches at 1000 yards; this has been known since the 1930's
Long before that, Gen Hatcher (then Major) wrote about it in his book, "Machine Guns, 1917".

In the book he has a chart showing the drift of the 1903's 1905 sights and 1906 Ammunition, to 2800 yards.

Briefly he shows the drift with this combination to be 1 ft at 1000 yards, 2 feet at 1200, 4 at 1400, 6 at 1600, 9 at 1800......and 36 feet at 2800 yards.

I realize few of us shoot past a mile, and those that do successfully know the formula's to compensate.

Some sights for military rifles had the correction built in but WWII shortened the ranges between combatants quite a bit, no longer were soldier dropping rounds into their adversary's trenches at 2000 yards.

I put a dial indicator on my '98 Krag and its 1901 ladder sight, it seems to move a tad to the right as you push the slider up. (I just roughly checked, I'll mount the rifle solid and try it again.)

When we went to the M1903A3, and its peep (rear) sights, they were limited to about 800 yards in elevation (the Garand & M14 goes a bit further).

But for the average soldier its not something to be concerned with (excluding snipers and SDMs).

It's still taught to machine gunners or was, I taught "spin drift" when I use to run MG schools with the M60. Now it seams most people use machine guns as an automatic rifle instead of a crew serve weapon to support troop in the advance.............any way.

For the new shooter trying to determine which way to move the sights to change the impact, Spin Drift, the Coriolis Effect, etc etc, should be put on hold, there are too many other things to worry about. Wind and Mirage are more critical.

With the M16 and qualification going to 300 yards, its much to do about nothing. If you're shooting 1000 yard service rifle matches at 800, 900 & 1000 yard you're going to have (or should have) a specific zero for those ranges which would take into account spin drift.

The Coriolis effect is something different, besides distance, the lay out of the range makes a difference. It will be different if your range lies east and west or north and south, and the latitude and longitude of that range, (that's why we have "score or data books").

So in short, for the new shooter, DON'T WORRY ABOUT IT, Learn the fundamentals and learn to read wind and mirage. You'll be much further a head.
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Old January 28, 2013, 09:48 AM   #10
jrothWA
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First of all, are the sight @ "zero" on the rifle?

For this sighting - in use good ammo not just any surplus ammo available.

Meaning is the front centered on its dovetail? is the rear the same.
This is called mechanical zero, now shoot at 100 yds and determine the impact, move the front towards the group moving it by the multiple of the distance from aiming times 0.008".
0.008" is the distance that will induce a 1" change @ 100 yds. the same for the elvaation (more later).

With the windage @ "zero", now the elevation, @100yds, turn the rear elevation down to bottom and bring it up, counting eight (8) clicks.

Determine the offset correction and either FILE the blade top down to RAISE the impact or replace with a new unused front sight to LOWER the impact.

When everything is a zero, you're done.

As a new M1 owner, try and buy the Kuhnhausen book "The U.S. .30 caliber Gas Operated Service Rifles. It has valuable information on maintaining your Garand.
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Old January 28, 2013, 10:21 AM   #11
Bart B.
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Kraig, I think Hatcher's drift data was based on the 150-gr. spitzer bullet; I've seen that info before and it is correct. The 173-gr FMJBT bullet was used for data derived in the 1930's. I should have specified the bullet as one's gonna spin faster than the other when it leaves the barrel.
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