sighting in an eotech

kasper7106 · 03-23-2011, 17:16

I just mounted an eotech 512 on my M&P15OR. I havent been able to get out to my range on my farm due to weather so I have to take it to the local indoor range. I would like to zero it in at 100yrds but the indoor range is only about 25yrds long. My question is; at 25yrds where should the point of impact be (couple inches high or low) so when I take it out to 100yrds it should be pretty close

Captains1911 · 03-23-2011, 18:00

Depends on ammo, but with a 100yd zero you should be about 1.5" low at 25yds.

Just curious, do you plan on shooting out past 100 yds often? If so you may want to explore a 50yd zero.

rjrivero · 03-23-2011, 18:03

There is an EOTECH target for sighting in at 25 yards that will get you on target at 300m.

It's located HERE.

trlcavscout · 03-23-2011, 18:05

I second the 50 yd. I sited my 512 on my front site post which was already set for 50 and its right on.

expatman · 03-23-2011, 18:05

Quote:

Originally Posted by rjrivero

There is an EOTECH target for sighting in at 25 yards that will get you on target at 300m.

It's located HERE.

Link is not working. Please try again.

rjrivero · 03-23-2011, 18:06

Quote:

Originally Posted by expatman

Link is not working. Please try again.

Took a couple seconds for me to clean it up. Try it now. If it doesn't work for you, please send me a PM.

expatman · 03-23-2011, 18:57

Works now. Thanks.

TSAX · 03-23-2011, 18:59

Quote:

Originally Posted by rjrivero

There is an EOTECH target for sighting in at 25 yards that will get you on target at 300m.

It's located HERE.

It works now

kasper7106 · 03-23-2011, 21:04

As soon as my fields dry up I will sight it in at 50 or 100yrd. but for now 25yrd is as far as I can go in the indoor range. I will put it at an inch and a half low at 25 and go from there. thanks

JASV.17 · 03-24-2011, 07:17

50 yard zero is what I want as well, but my range only has 25 and 100. So until I can get to one, I'm zeroed at 25. I did it dead on at 25, which puts me about 6" low at 100.

Captains1911 · 03-24-2011, 07:39

A 50 yd zero should put you a little more than 1 inch low at 25 yds.

WoodenPlank · 03-24-2011, 07:41

Quote:

Originally Posted by JASV.17

50 yard zero is what I want as well, but my range only has 25 and 100. So until I can get to one, I'm zeroed at 25. I did it dead on at 25, which puts me about 6" low at 100.

I assume you mean that the optic is 6" low at 100?

Captains1911 · 03-24-2011, 07:44

Quote:

Originally Posted by WoodenPlank

I assume you mean that the optic is 6" low at 100?

You're right, that doesn't make sense. With a 25yd zero the POI should be high at 100 yds. Note the x-axis in this plot is in meters.

JASV.17 · 03-24-2011, 09:51

Quote:

Originally Posted by WoodenPlank

I assume you mean that the optic is 6" low at 100?

Oops, yes, that's what I meant. Horrible wording on my part, sorry.

surf · 03-24-2011, 11:34

For practical zeroing purposes, it doesn't really matter at 25 yards. As long as you are within +/- 1.5" to 2" at 25 yards you will be safely on paper within a max spread of around +/- 5-7 inches at 100. This will allow you to quickly dial in your 100 yard zero. Technically your 100 yard zero will print about 1.5" low at 25 yards but it is hard to really estimate the 100 yard zero from dialing in at 25 yards as the variable of measurement and shooter accuracy is harder to control. In other words more consistency in zero is gained from shooting farther away. 100 yard zero is a great zero. My second favorite zero, but only by a slight margin.

WoodenPlank · 03-24-2011, 12:37

Quote:

Originally Posted by surf

For practical zeroing purposes, it doesn't really matter at 25 yards. As long as you are within +/- 1.5" to 2" at 25 yards you will be safely on paper within a max spread of around +/- 5-7 inches at 100. This will allow you to quickly dial in your 100 yard zero. Technically your 100 yard zero will print about 1.5" low at 25 yards but it is hard to really estimate the 100 yard zero from dialing in at 25 yards as the variable of measurement and shooter accuracy is harder to control. In other words more consistency in zero is gained from shooting farther away. 100 yard zero is a great zero. My second favorite zero, but only by a slight margin.

Out of curiosity, surf (Murphy, too, if you come across this)...

Any preference for zeroing on a Mk. 18 or similar setup?

cowboy1964 · 03-24-2011, 15:30

Either 50 or 100 yard zeros are great. Each has their own advantage. I doubt it makes any real difference in the real world for 99% of people.

Here's a tidbit: the POI is exactly on the bottom ring of the Eotech at about 6 yards. Great if you need to make a precision close-range shot.

locosteelersfan · 03-24-2011, 17:03

tagging....ordered a 512 this week.

surf · 03-24-2011, 19:05

Quote:

Originally Posted by WoodenPlank

Out of curiosity, surf (Murphy, too, if you come across this)...

Any preference for zeroing on a Mk. 18 or similar setup?

My work weapon is a Colt M4A1 with the genuine MK18 10.3" barrel. For my purposes I use a 50 yard / 200meter zero just to keep consistency in my normal 50 yard BZO with any length barrel. I note that my outer zero is indeed consistent to the roughly 220 yard outer zero. This is with 55gr up to 77gr with normal variances found between the different bullets and weights.

I also find that my hold offs seem consistent out to about 400 yards so IMO barrel length is not the factor for me when choosing a zero, but rather shooting type / preference. I will also say that I am pretty darn comfortable with a 100 yard zero also.

I do not really care as much for the 25m or closer zero's that may have been common years ago in the MP5 days, if you are referencing the MK18 as an up close primary weapon. The MK18 can still reach out and I just don't prefer the bigger +/- variance at mid ranges. Anything closer than say 25m gives way too much variance at only small distance changes because of the height overbore issue.

WoodenPlank · 03-24-2011, 22:54

Quote:

Originally Posted by surf

My work weapon is a Colt M4A1 with the genuine MK18 10.3" barrel. For my purposes I use a 50 yard / 200meter zero just to keep consistency in my normal 50 yard BZO with any length barrel. I note that my outer zero is indeed consistent to the roughly 220 yard outer zero. This is with 55gr up to 77gr with normal variances found between the different bullets and weights.

I also find that my hold offs seem consistent out to about 400 yards so IMO barrel length is not the factor for me when choosing a zero, but rather shooting type / preference. I will also say that I am pretty darn comfortable with a 100 yard zero also.

I do not really care as much for the 25m or closer zero's that may have been common years ago in the MP5 days, if you are referencing the MK18 as an up close primary weapon. The MK18 can still reach out and I just don't prefer the bigger +/- variance at mid ranges. Anything closer than say 25m gives way too much variance at only small distance changes because of the height overbore issue.

The longest range I currently have access to is only 150 yards. I have my M2 zeroed at 25 yards, and (with 55grn) it comes back to zero right at 150. It is consistent enough that I can ring the gong at 150 every time offhand. I really don't anticipate EVER taking a shot past 150 with it (hell, if I have to fire a shot in anger with it, there is a serious problem), so the 25 yard zero works fine for my needs. 75grn TAP 5.56 hits about 18-24" high at 150, though.

surf · 03-25-2011, 13:14

Quote:

Originally Posted by WoodenPlank

The longest range I currently have access to is only 150 yards. I have my M2 zeroed at 25 yards, and (with 55grn) it comes back to zero right at 150. It is consistent enough that I can ring the gong at 150 every time offhand. I really don't anticipate EVER taking a shot past 150 with it (hell, if I have to fire a shot in anger with it, there is a serious problem), so the 25 yard zero works fine for my needs. 75grn TAP 5.56 hits about 18-24" high at 150, though.

OK, I am a bit confused. Ballistically what you post makes no sense to me 55gr or any grain bullet. A zero at 25 yards being your first crossing of line of sight (POA/POI), your second crossing of line of sight (POA / POI) should be around 375 yards. With a 25y zero you should be around 8" high at 150 yards.

If I were maxing out at 150 yards, I might opt for a 100 yard zero because you will only have a low offset all the way out to 100 and will only have a drop of about .5" out to 150. But this is really splitting hairs at this point.

WoodenPlank · 03-25-2011, 13:19

Quote:

Originally Posted by surf

OK, I am a bit confused. Ballistically what you post makes no sense to me 55gr or any grain bullet. A zero at 25 yards being your first crossing of line of sight (POA/POI), your second crossing of line of sight (POA / POI) should be around 375 yards. With a 25y zero you should be around 8" high at 150 yards.

If I were maxing out at 150 yards, I might opt for a 100 yard zero because you will only have a low offset all the way out to 100 and will only have a drop of about .5" out to 150. But this is really splitting hairs at this point.

You are probably thinking of a 16" barrel(ETA: At least, I would assume so...). This is on a registered SBR with a Mk. 18 upper.
Also, at 150 I rarely shoot paper. Instead, I am just shooting steel, and getting solid hits with nearly every round. If there is still an offset, I am not seeing it, as everything is hitting a roughly 16-18" plate.

surf · 03-25-2011, 17:30

As mentioned my primary rifle is a MK18 10.3" barrel. I have no noticable variance in zero or impacts all the way out to 400 yards from a 50 yard zero. It would be nearly impossible ballistically speaking to lose enough velocity where any SBR length barrel out of this platform would have a true 25yard zero and then be truly zero'd again at 150 yards.

So for your scenario quoted, you need to remember that with a 25 yard zero you would be roughly 8" high at 150 yards. So you are shooting 16"-18" plates there is your variable. You could be hitting 8" high and still gonging the plate. But if you shot at say a 4" plate from 25 yards and hit dead center, I would pretty much guarantee at 150 yards you would be missing high every time if you were holding dead center of a 4" plate.

Hope that makes sense. When you are talking zero, we really aren't talking torso sized zero. However in a battle rifle with a dot optic zero's can be nit picking when we are talking center of mass holds on a man or torso sized target.

WoodenPlank · 03-26-2011, 06:00

Quote:

Originally Posted by surf

As mentioned my primary rifle is a MK18 10.3" barrel. I have no noticable variance in zero or impacts all the way out to 400 yards from a 50 yard zero. It would be nearly impossible ballistically speaking to lose enough velocity where any SBR length barrel out of this platform would have a true 25yard zero and then be truly zero'd again at 150 yards.

So for your scenario quoted, you need to remember that with a 25 yard zero you would be roughly 8" high at 150 yards. So you are shooting 16"-18" plates there is your variable. You could be hitting 8" high and still gonging the plate. But if you shot at say a 4" plate from 25 yards and hit dead center, I would pretty much guarantee at 150 yards you would be missing high every time if you were holding dead center of a 4" plate.

Hope that makes sense. When you are talking zero, we really aren't talking torso sized zero. However in a battle rifle with a dot optic zero's can be nit picking when we are talking center of mass holds on a man or torso sized target.

Point taken. I will be on the range tomorrow, and will see about actually printing the offset on paper. That plate is way too big to get a solid idea of what that offset really is.

surf · 03-26-2011, 12:09

Just another thing to think about, when talking about a battle rifle and a red dot optic or even irons, if you are talking a true zero it is hard to talk precision and zero as distance increases. The outer zero is often hard to truly determine due to the limiting factor of the rifle, the dot optic, iron sights or the shooter variable. However if you look at it in a battle field application the 25yard zero works well on a man sized target out to 300m+. This is why a center of mass hold no matter the distance will have an impact on a man sized target. An 8" variance will still hit a human torso on a center of mass hold no matter the distance out past 400m +. But from a true ballistics standpoint there is a mathematical calculation that comes up with where your bullet will cross line of sight at 2 different points.