Rifle Scopes Eotech exps 3-4

[GhengisAhn175]

Although this isn't a riflescope, I'm not a member of ar-15 so thought if might post here.

Wondering if anyone knew the measurement specifications of the exps 3-4 reticle. I know the ring is 65 Moa and each dot is 1 Moa.

The Manual only states it's calibrated for a .223 and dot 1 is 0-300, 400, 500, 600.

I have this mounted on a 308 and zeroed at 100 yards. I figured if I could get the distance the dots are spread apart in mils or Moa, I could input that into a ballistics calculator for my handloads and figure out the true value of the other 3 dots.


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[Redmanss]

My weak google-foo didn't come up with anything, but that doesn't mean you can't come up with the numbers even if they're not openly available. Map the reticle. While this may not be the easiest to do with a 1x optic, it can still be done. Bench the optic and place a yard stick downrange at exactly 100yds/m, whichever you got and want to do the math with. Run a magnifier/spotter behind the optic and figure out exactly what the measurements are on center of each dot. You now know what they're at.

I would highly recommend starting with a 200yd zero for it.

 

[GhengisAhn175]

Redman, I'm not understanding the method. Let me see if I can get this right using a 100 yard zero example.

1. Set up at 100 yards with a target at the lowest portion of target possible (as I will be using the other dots my poi
Will move up with my 100 yard zero dot).

2. Measure out the poi of the 2nd, 3rd & 4th dot.

Say for example my 2nd dot
Impacts 5 inches high, 3rd impacts 10 and 4th impacts 15.

I don't know how I can use that data?

Unless what I'm supposed to do is go off my ballistic calculator and plus/minus the drops since I know my
Loads velocities?

My ballistic app says 200yards = -3.4 inches (assuming that's what path (in) means, 300 is -14.5 and 400 is -34.2

Am I running into this issue because I chose a 100 yard zero instead of the 300 yard/meter as it was designed
For military ballistic use?

Let Me know if anything I'm saying is crazy


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[JBomb]

I can't find the picture right now but of the top of my head it was something like this....

5.6 moa. 400 yard
10.2 moa. 500 yard
15.8 moa. 600 yard

It's probably not exact but it's close.

 

[GhengisAhn175]

Jbomb I google searched the pics. Would love to know where you got that from! All I could find is the reticle blown up and lines pointing to each dot and what it's ballistic ally set for (military 5.56 out of a 16" barrel at 2970 fps)


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[corym468]

 

[Redmanss]

Cory came in with the pic, so awesome there and now you don't need to map it, but I'll still explain what I was talking about doing.

What I was talking about was mapping the reticle without firing. You are measuring the reticle for its subtensions at an exact distance. While this method isn't typically used for 1x optics, it's the same way you find the exact point in a variable SFP optic for using the reticle accurately for measurements. I am basically saying to reverse engineer the reticle by measuring the distances between dots.

As for your holds, yes, your 100yd zero is what's throwing you off. Even with a slower shooting .308 (assuming it's on a carbine of sorts), your trajectory out to 200yds will be within an effective "kill" zone the entire flight of the projectile. You can certainly tweak this with your particular load to see where you can have an acceptable deviation for your particular shooting. The sweet spot for you will probably be between 200-250yds, and should also coordinate with a close range zero opportunity around 50yds.

 

[GhengisAhn175]

Thanks for the pic Cory!!

Redman, I'll try out a different zero. I did my research and went with the 100 for reasons I can't remember but it "made sense".

The argument I came across was the 50/250 or 50/300 m zero where the bullet trajectory becomes the same poa/poi was for a very specific set up: military m16a2 using 5.56 ball going 2790 fps. People emulated that because it was (what the military did) not knowing that changing factors such as barrel length, ammunition, even the rifle threw those #'s off. Seeing how it was flawed I decided to go with the 100 yard zero as you can hold under for cqb precision shooting.

Now going back to trying out a longer zero, is there a way I could map out the arc of my round (using ballistic app maybe) for me to know if I held say a 50 yard zero, where
The next POI would be out at distance?


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[GhengisAhn175]

* inception!! The answer just dawned upon me. Use the ballistic chart app!!!...

Thanks redman!


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[GhengisAhn175]

So from what I gathered here is what I've calculated so far as long as picture is correct with MOA distances:

Rifle shooting 175 gr smk at 2420 fps with a 100 yard zero using an exps 3-4:

First dot is 100 yard zero
Second dot = 326 yards
Third dot= 458 yards
Fourth dot = 593 yards.

With a 100 yard zero I really don't have a short/long range poi relativity unlike a 25 yard zero which has a 357 yard poi relativity or a 50/196.

Guess I can take it from here and figure out what I want! Appreciate the direction fellas




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