Sighting in rule of thumb

[Lost Lake]

LostLake- I promise that I will get back to you about this subject. I was looking at the target and I have two holes dead center about 2 inches high. My problem is that I don't recall if they were my first two shots! Seriously. I shot the gun two weeks ago I believe. I asked my son and he was unsure also. It might have been shooting high but I thought it was shooting low. I could be wrong. All I can say is that I use the Nikon scope with a BDC reticle. I zeroed it to 100 yards. According to Nikon stats it should be good to 600 yards. I don't shoot my MSR's with iron sights as I have never needed to.BTW- it shoots really well at 100 yard zero with that scope.

Thanks Don5.

If you zero it at 100, you will be low at just about every other distance you shoot at. The bullet will come up to the 100 yard line then start to drop from there. It's not like shooting at 25 yards where the barrel is pointed way up to intersect with the line of sight at such a close distance that it rises above the line of sight and falls again.

If you crank in some BDC that is calibrated for your 3000fps round you will be good out to 600 or so, but you have to really crank up the elevation....

 

[don5]

Thanks Don5.

If you zero it at 100, you will be low at just about every other distance you shoot at. The bullet will come up to the 100 yard line then start to drop from there. It's not like shooting at 25 yards where the barrel is pointed way up to intersect with the line of sight at such a close distance that it rises above the line of sight and falls again.

If you crank in some BDC that is calibrated for your 3000fps round you will be good out to 600 or so, but you have to really crank up the elevation....

That is why I use the BDC reticle. Of course, in the old days it was called "Kentucky windage". Now, we have scopes that compensate for bullet drop along with laser rangefinders and fancy wind drift squeeze bottles.

 

[cyphertext]

Another point I have to make is you can't be zeroed at 25 yards and 300 yards at the same time with a 55gr bullet, unless you reload and leave some powder out.

You just can't do it.

When you use the 25m zero, per the chart, you would be back at zero at in roughly 350m, and would be about 6 inches high at 300m, assuming you use the same aperture. However, you don't use the same aperture, you use the large aperture when shooting at less than 200m. Because the apertures are not on the same plane, POI and POA will be affected. Every little shift makes a big difference at 300m, so you are going to be less than 6 inches high at 300, and when aiming at COM, you will score a solid hit. After all, it is a battle sight zero, not a competition zero.

If you want a closer 300m zero, but wish to zero at the point where the trajectory first crosses the line of sight, then you would go with the 36 yard (33m) zero that was used by the Marines.

 

[Lost Lake]

That chart is for the M855 (62gr) round. ^^^^^

The sight-in directions tell you to click past the 6/3 or 8/3 setting to mechanically zero the rifle, then after sighting in at 25 yards, to set the rear elevation back to 6/3 or 8/3.

I hope nobody reading this thinks we can zero at 25 yards and be on at 300 and anywhere close to on anywhere in between. If you look at the graph with the 25/50/75/100 yard zeros, this one shows a M193 55gr and a 14.5" barrel, you'll see a 25 yard zero doesn't come back down until 375 yards and is over 10 inches high at 200 yards. That's with a 2.5" sight, and will be worse with a 2.8" sight and 16" barrel!

The 50 yard zero is much better, and a 200 yard zero is probably the best. If I only had a 25 yard range, I'd sight in to be 1 1/4" low at 25 yards and hold dead on all the way out to 250 yards.

 

[oneyeopn]

wow....LMAO....I came through all of that to here!!!

 

[cyphertext]

That chart is for the M855 (62gr) round.
^^^^^

There isn't much difference.

http://www.box.net/shared/static/pg9s5r0xl5.jpg

The sight-in directions tell you to click past the 6/3 or 8/3 setting to mechanically zero the rifle, then after sighting in at 25 yards, to set the rear elevation back to 6/3 or 8/3.

Not with the M4...Please go read the tech manual. For the M4, with the 14.5 inch barrel, you set it on 3/6, sight in at 25m...This is how the friggin' Army did it. You only click past and use the Z setting when sighting in the 20" barrel.

Copied directly from FM 3-22.9 pg. 5-1

GlobalSecurity.org - Reliable Security Information

Special Instructions
Ensure that—
• The rear sight is on the proper setting (zero; M16A2/3=8/3+1; M16A4=6/3+2; M4=6/3).

Notice that the rear sight settings are different depending on which rifle you are zeroing.

I hope nobody reading this thinks we can zero at 25 yards and be on at 300 and anywhere close to on anywhere in between. If you look at the graph with the 25/50/75/100 yard zeros, this one shows a M193 55gr and a 14.5" barrel, you'll see a 25 yard zero doesn't come back down until 375 yards and is over 10 inches high at 200 yards. That's with a 2.5" sight, and will be worse with a 2.8" sight and 16" barrel!

The 50 yard zero is much better, and a 200 yard zero is probably the best. If I only had a 25 yard range, I'd sight in to be 1 1/4" low at 25 yards and hold dead on all the way out to 250 yards.

I don't think anybody is saying that if you use the 25 / 300 m zero that you will be on at any range. If you use this zero, it gets you close at 300m. If you have access to 300m, you would verify your zero and adjust. There are no settings on the rifle for less than 300m, unless you modify the rear sight for the improved battle sight zero. For less than 300m, you use hold under...you have to know your rifle and have a lot of practice. I agree with you that if you are not engaging targets at 300m or greater, then this is not going to be the best sight in method. I think we have beat this horse as much as we can.

 

[Lost Lake]

If we are having guys sight in at 25 yards and be off by 10" at 200.... TEN INCHES!!! when they have an adjustable rear sight!!! Then something is definitely WRONG in our army today....

I'd like to read the manual, but the link you posted is 21 megs, and I'm running at 250K here today, so I'm not downloading the entire thing.

I'm very disappointed the military would teach this method. Even if the sights couldn't be adjusted far enough, they could at least train shooters to sight in an inch low at 25 yards. The weapon would be more than twice as accurate at all points from 25 to 800 yards.

This guy has the right idea. BattleField Sighting

In fact if you look at he bottom section of his web page he details the USMC sight-in procedure which is what we we using in the army back in the 70's, at least my group was.

Doesn't this make more sense? Why be so far off when it is so simple to be much closer?

 

[cyphertext]

It may be splitting hairs, but some would say that the rear sight is not "adjustable", it just allows you to change a setting for ranges. Think of it as similar to a bullet drop compensation reticle in a scope. Elevation is really adjusted at the front sight. It really is only useful on the known distance ranges. In active combat, you would use hold over though instead of changing the ranges. Much quicker.

I think you may be mistaken about using the improved battlesight zero back in the 70's. I don't think Col. Santose had developed it prior to the 90's, and it was not an approved sight in system per the TMs when I was in (89-95). That system requires a modification to the sight, and your standard units would not allow you to make a modification that was not specifically detailed in the Tech Manual.

I do agree though, for my type of shooting today, 50 /200 is a better zero for me. My red dot is set up for 50 yard zero.

 

[shoot870p]

lost lake you seem to be slipping

TASK- Zero an M16A2 Rifle
CONDITIONS- On a 25-meter range, given an M16A2 rifle, 18 rounds of 5.56-mm ammunition, a 300-meter zero target, and sandbags for support.
STANDARDS- Using 18 rounds or less, the soldier must battlesight zero his rifle by achieving five out of six rounds in two consecutive shot groups within the 4-centimeter circle. Bullets that break the line of the 4-centimeter circle will be used in evaluating the soldier's performance.

TRAINING AND EVALUATION-

1. The M16A2 rifle has two adjustable sights -- front and rear. Elevation adjustments are made using the front sight, and elevation changes and windage adjustments are made using the rear sight.

2. The sight systems.

a. The rear sight has an elevation knob with range indicators from 300 to 800 meters and two apertures for range. One aperture is marked 0-2 for short range from 0-200 meters and an unmarked aperture for normal range from 300 to 800 meters.

(1) The 0-2 (large) aperture is used for short range (Figure 107). This aperture is used only when the rear sight is all the way down. The 8/3 (300-meter) mark on the elevation knob is aligned with the index mark on the left side of the receiver.
(2) The unmarked (small) aperture (Figure 108) is used for normal range. This aperture is used for most firing situations. It is used in conjunction with the elevation knob for 300- to 800-meter targets.

b. The rear sight also consists of a windage knob on the rear side of the sight (Figure 109).

(1) Each click of the windage knob will move the strike on the round from 1/8 inch (.3 centimeters) at 25 meters to 4 inches (10 centimeters) at 800 meters.
(2) A windage scale is on the rear of the sight and the windage knob pointer is on the windage knob.

c. The front sight consists of a rotating sight post with a spring-loaded detent (Figure 110).

. M16A2 Rear Site
Rear sight

M16A2 Unmarked aperature and Windage Knob
(Left) Unmarked aperture (Right) Windage knob.

M16A2 Front Sight
Front sight

The front sight is moved up or down when zeroing the rear sight

Once the rear sight is zeroed, the front sight post should not be moved

Each notch on the front sight will move the strike of the bullet from 3/8 inch (0.9 centimeters) to 2 3/4 inches (7 centimeters) at 200 meters.

3. Sight adjustments.

a. Rear sight.

(1) To adjust windage or move the strike of the round, turn the windage knob counterclockwise to move the strike to the left and clockwise to move the strike to the right (Figure 109).
(2) To adjust elevation, turn the elevation knob until the desire range is indexed at the index mark on the left side on the sight (Figure 107).

b. Front sight. To adjust elevation, depress the detent and rotate the sight post (Figure 111). To raise the strike of the round, rotate the sight post in the direction of the arrow marked UP. Reverse the direction of rotation to lower the strike.

4. Zero the rifle. The following steps will establish a zero at 25 meters, your M16A2 rifle sights will be set with a 300-meter battlesight zero.

a. Establish mechanical zero on the rifle.

(1) Align the windage indicator mark on the 0-2 aperture with the center line of the windage scale (the unmarked aperture is up) (Figure 109).

. Depress Detent
Figure 111. Depress detent..

(2) Rotate the elevation knob down until the range scale 8/3 (300-meter) mark is aligned with the mark on the left side of the receiver (Figure 107).
(3) Rotate the front sight post up or down as require until the base of the front sight post is flush with the top of the sight post well.

b. Zero at 25 meters.

(1) After setting the front and rear sights to mechanical zero, the elevation knob is rotated up (clockwise) one click past the 8/3 (300-meter) mark. The elevation knob will remain in this position until the battlesight zeroing has been completed.

NOTE: Any changes in elevation required during the zeroing procedures will be made using the front sight post only.

(2) Carefully aim and fire each shot of a three-shot group at the circle on the silhouette (Figure 112).
(3) If your shot group is not within the circle on the silhouette, use the squares on the target to determine the required clicks to move your next shot group into the circle (Figure 112).

NOTE: The squares are numbered around the edges of the target to equal the number of clicks required to move the shot group to the circle.

(4) To raise your next shot group, rotate the front sight post UP (clockwise). To lower your next shot group, rotate the front sight post DOWN (counterclockwise). One click will move the strike of the round one square on the target.
(5) To move the shot group to the left, turn the windage knob counterclockwise. To move the shot group to the right, turn the windage knob clockwise. Three clicks of the windage knob will move the strike of the round one square on the target.
(6) Continue to fire three-round shot groups and make corrections until you have a tight shot group in the circle on the silhouette.

. 25 Meter Zero Target for the M16A2
25-meter zero target.


(7) If your shot group is within the circle, your rifle is now "calibrated."
(8) To place your 300-meter zero on the rifle, you must rotate the elevation knob one click counterclockwise. The 8/3 (300-meter) mark on the elevation knob should now be aligned with the index mark on the left side of the sight.

NOTES: 1. There are clicks between the range numbers as you turn the elevation knob. Use these clicks if you need more elevation past a certain range number to hit a target.
2. The unmarked aperture is automatically zeroed to 200 meters. Use the 0-2 aperture when shooting at night or at close ranges; for example, in an urban environment or in dense jungle.

5. Sight setting. your rifle sights should be kept set to a combat zero of 300 meters. If you are told to engage a target at a longer range; for example, 500 meters:

a. Rotate the elevation knob so that the desired range mark is aligned with the index mark on the left side of the sight.
b. Engage the target.
c. When the engagement is over, return the sight to the 300-meter setting.

NOTE: When the rifle has been zeroed to 300 meters, all other ranges on the elevation knob are also zeroed.

 

[Gyrene6891]

No matter how you got there, the firing line was always different. The whole reason you shot the short course was to get some where close at the 300. But qualification was started at the 200 then move to the 300 and then the 500. There were additions/subtractions for different positions, off hand, sitting, kneeling, prone. Then everything changed the next day because you now had either bright sunlight or it was now cloudy. Then there was the wind on day and a different wind the next. That was for the known distance coarse, of course all that went out the window when you were guessing at the distance and the cross wind, not to mention the other guy shooting back...

 

[Lost Lake]

TASK- Zero an M16A2 Rifle

(1) After setting the front and rear sights to mechanical zero, the elevation knob is rotated up (clockwise) one click past the 8/3 (300-meter) mark. The elevation knob will remain in this position until the battlesight zeroing has been completed.

(8) To place your 300-meter zero on the rifle, you must rotate the elevation knob one click counterclockwise. The 8/3 (300-meter) mark on the elevation knob should now be aligned with the index mark on the left side of the sight.

I don't know why you guys keep saying I'm wrong, when this post shows I'm right!

You DO NOT zero at 25 meters without throwing the rear sight off ahead of time.

So you throw the sight, hit a target you could dang near spit on, then return the sight back to where it should be. At this point you will be zeroed at something around 40 meters I would bet..... And a LOT closer to 300.

Now fess up! How many of you weren't doing this?

 

[cyphertext]

I don't know why you guys keep saying I'm wrong, when this post shows I'm right!

You DO NOT zero at 25 meters without throwing the rear sight off ahead of time.

So you throw the sight, hit a target you could dang near spit on, then return the sight back to where it should be. At this point you will be zeroed at something around 40 meters I would bet..... And a LOT closer to 300.

Now fess up! How many of you weren't doing this?

Reading comprehension is key....that is with the M16A2...again, different with the M4.

Posted again from the field manual...

Special Instructions
Ensure that—
• The rear sight is on the proper setting (zero; M16A2/3=8/3+1; M16A4=6/3+2; M4=6/3).

So which rifle are you talking about here? If you are talking about your S&W M&P 15OR, you would need to follow the instructions for the M4.

 

[Lost Lake]

Reading comprehension is key....that is with the M16A2...again, different with the M4.

Posted again from the field manual...

Special Instructions
Ensure that—
• The rear sight is on the proper setting (zero; M16A2/3=8/3+1; M16A4=6/3+2; M4=6/3).

So which rifle are you talking about here? If you are talking about your S&W M&P 15OR, you would need to follow the instructions for the M4.

I may be getting this now....

So the A2 and A3 you go one click past the 8/3 setting, the A4 is 2 clicks past the 6/3 setting, and the M4 stays ON the 6/3 setting!!!

AM I RIGHT?? WOO HOO!!!

I think I have it!!!

Okay, back to business. An OR has no sights....

And my 15A model has a rear Troy Battlesight, so none of this pertains to mine anyway. All these instruction are for carrying handle sights.

 

[cyphertext]

I may be getting this now....

So the A2 and A3 you go one click past the 8/3 setting, the A4 is 2 clicks past the 6/3 setting, and the M4 stays ON the 6/3 setting!!!

AM I RIGHT?? WOO HOO!!!

I think I have it!!!

Okay, back to business. An OR has no sights....

And my 15A model has a rear Troy Battlesight, so none of this pertains to mine anyway. All these instruction are for carrying handle sights.

You got it chief...and believe it or not, the target for the sight in target for the M4 is different than the one for the A2.
You might like these targets...should have posted them before. They have the zero instructions on them too.

http://www.bobdbob.com/~deneb/doc/targets/m4-carbine-zero.pdf

http://www.bobdbob.com/~deneb/doc/targets/m16a2-25m-zero.pdf

I don't have a carry handle, but I have the same sight system as the carry handle on my .22lr AR. I have a Matech on my Sport, and the sight in is very similar for it as well.

 

[stavman11]

hey....

what Happened to this thread


It was very entertaining


Sorry guys 1st day in 6 days with Coffee... and im all JACKED UP

 

[Lost Lake]

It took these guys a while but I think they finally beat it into my head....

Sooooo I went out and sighted in my 15A yesterday FINALLY...

First three shots at 35 yards were 1" right and 1" low. I bumped it left an inch and left it there. Done. It was THAT close from the factory. The red dot that I slapped on it was perfect right out of the box. I bet that has never happened.

Anyway I had a good time and my son and eldest daughter had a blast shooting the AR and a slew of handguns.

The warden went along and finally believes me now that she can't shoot my 642 real well, and for now she is keeping a 9c and M&P22 by her side. She doesn't like the long trigger pulls on the 642, 6906, 3913 and 4513. Oh well, my good because I get my 642 back to pocket carry this summer.