How To sight in the iron sights on SCAR 16?

[sirgilligan]

Hunting trip is coming up quickly and I will take the SCAR 16 to sight in and play with while we are not hunting. The trip is a week long so there will be plenty of time.

How did you sight in your SCAR 16 iron sights?

Which setting did you use for the rear sight?

At what range?

The manual says set the rear sight to 3 and use this to sight in at 25m/300m.

300 meters is 328 yards.

From a ballistic calculator:
With the sight height at 3.5 inches and a zero at 328 yards using M855 ammo you cross zero at about 45 yards and 328 yards. You are 5.7 inches high at 200 yards.

If you sight it at 250 yards you cross zero at 60 yards and 250. At 100 yards it is 1.5 inches high. It peaks at 2.3 inches high at 150 yards.

How much does one click change on the rear sight actually change the bore angle?

If you have sighted in your iron sights at what distance did you do so and what are the results at different ranges? Say you sighted it for 100 what are you seeing at 200?

Thanks.

[Gos]

mine was "factory zero'd" but the rear windage was way off, so I recentered it and am doing my zeroing from scratch. I'd really like to do a 50/200 zero instead of the 25/300, and i'm wondering if I can just do the 50 @ position 2 on the rear, and keep the rest of the elevation clicks useful?

[sirgilligan]

I am wondering the exact same thing. What effect does each elevation click have.

If know one knows, I will be figuring it out at the end of this week.

From my ballistic calculations if you sight the SCAR in for 200 yards you may see something like this:

50 yards should be -1.0". ( one inch low)
75 - 80 yards should be -.01" to 0.1"
100 yards should be 0.5" (half an inch high)
130 - 180 yards should be 0.9".
200 yards should be 0.0"
225 yards should be -1.0" (one inch low)
250 yards should be -2.4"
300 yards should be -6.4"

That should be a "sweet" spot for sighting in the SCAR.

Being bored sitting here at the computer I also ran 220 yards zero for the SCAR.

45 yards -1.0"
70 yards 0.0"
100 yards 0.9"
130 - 160 yards 1.4"
220 yards 0.0"
250 yards -1.5"
300 yards -5.3"


Here are some "double zero" values:
40 yards and 350 yards
50 yards and 295 yards
60 yards and 255 yards
70 yards and 220 yards
80 yards and 195 yards
90 yards and 175 yards
100 yards and 160 yards
110 yards and 140 yards
120 yards and 130 yards
-pivot point-
130 yards and 120 yards
140 yards and 110 yards
...

Interesting observation, zero at 130 yards:
60 yards -1.0"
190 yards -1.0"

From 60 to 190 yards with only 1" variance. That is another "sweet" spot!

Just some mathematical data, not real world. But I did run the calculations for an M4 and the reported real world data matched up so I am confident that these estimates should be reasonable.

I am glad I added this ability to the Gun Log app. It is proving entertaining at least, next weekend it should prove useful.

[skipper]

Just providing this for those who may be interested.

According to the military manual for the Mk16 & Mk17 initial BZO is set at 25meters (82 ft). Setting the rear sight to "3" gives a battlesight zero @ 25/300 meters. Setting the rear sight to "2" gives a battle sight zero @ 25/250 meters.

Mechanically zero the rear sight (align the white lines) for windage then leave it there as all zeroing for SCARs is done with the front sight.

Sight initially @ 25 meters then check zero at distance.

The official military 25 meter BZO template provides the following information:

1. Point-of-impact is 24mm below Point-of-Aim;
2. Each grid square measures 7mm;
3. 1 click of the front sight elevation is 1.5 squares or 10.5 mm;
4. 1 click of the front sight windage is 1 square or 7 mm.

Note: mm/inch conversion is 25.4 mm/inch. Also, this template is good for all (military) ammunition types-M855, M262 issued for the SCAR.

Now if you don't have the template you can make your own 25 meter BZO target by placing POA/POI marks 24 mm apart and adjust groups with the click information above.

[sirgilligan]

Thank you for the information. I will use it this next week.

[snowman-zombie]

Good info, Thanks

[sirgilligan]

The official military 25 meter BZO template provides the following information:

1. Point-of-impact is 24mm below Point-of-Aim;

Am I to understand that a 25/300 meter sight in using #3 setting that at 25 meters the point of impact should be 24 mm below point of aim?

[ikantspeell]

I BZO at 36 yards....that's how I was taught in the Marines...and hey I can shoot.

[sirgilligan]

Okay, I have finally got this through my thick scull.

The military BZO recommendation for:
M855 is setting 3 for 300 meters (328 yards). Shoot at center of target at 25 meters (27.34 yards) and you should be -3.2 MOA low. 3.2 MOA at 25 meters is 0.83 inches. So you should be 0.83" low shooting at 27.34 yard target.

With this understanding I ran it through the ballistic drop estimator and found it to be:
27 yards -0.8", which is spot on!

To further check I see this:
34 yards = -0.1"
35 yards = -0.0"
36 yards = 0.1"
37 yards = 0.2"

So somewhere between 35 and 36 yards is the true zero for the ammo and BC and MV I have used.

So I see where 36 yards is dead on and 328 yards is dead on. So all of these values and recommendations are correct. Choose which one you want to use.

----------

Given all of that if you want to sight in on setting 2 for 200 meters or 219 yards:

25m = 27 yards -> -1.7"

25 yards -> -1.8"

38 yards -> -1.0"
39 yards -> -1.0"
40 yards -> -0.9"

55 yards -> -0.1"
58 yards -> -0.0"
60 yards -> 0.1"

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edit

M855 is setting 3 for 300 meters (328 yards). Shoot at center of target at 25 meters (27.34 yards) and you should be -3.2 MOA low.

1 MOA at 100 yards = 1.047"
1 MOA at 27.34 yards = ( 27.34 / 100) * 1.047 = 0.286"
0.266" * 3.2 = 0.916"

[skipper]

I think your calculations are probably correct. But let me give a little more information off the BZO 25 meter template.

"Point of Impact-All Barrels All Ammunition (-3.5 M.O.A. @ 25 m)"

So if you use the SCAR BZO target(or make your own) at 25m your Point of Impact should be (3.5 MOA)(.286")=1.001" below Point of Aim. That's the 24mm difference between aim and impact points on the target. 1 MOA @ 25m=.286 inches.
This situation doesn't change with either the 2 or 3 elevation setting on the rear sight. Your impact point should still be 1" below the POA with either setting. The sight setting just changes the secondary zero downrange; 300m on 3 vs 200m on 2.

The bullet crosses the line of sight at about 36yds, the traditional USMC BZO point for an M4/M16. This gives the Marines a downrange zero of 300 yards(274.3m). Army uses meters, the Marines use yards for BZO'ing.

One thing to note is that the sights on the SCAR are 3.5 inches above the bore ceterline versus 2.5 inches on, say, an M4/M16. That is why the 1" (24mm) difference between POA and POI using the SCAR 25m target. M4/M16 BZO targets don't have this difference.

Once you get set up at 25 meters, you do need to confirm at the secondary zero if your range allows.