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biko
11-03-2008, 2:14 PM
While at the outdoor range I zero'd the scope for 50/200 yds and the red dot for the same point of impact.

At an indoor range that allows rifles (for the fun of firing a few rounds), at 25 yds the POI was about 3 inches lower than the point of aim. To be expected given the range. (I am assuming of course the zero was held from when it was set).

It raised the question whether the red dot should be zero'd differently than the scope. Given the scope's 4x magnification its use would be generally 100-200 yds.

Since the red dot has no magnification and therefore is used at shorter distances, should it be zero'd differently than the scope?

Thanks!

xxdabroxx
11-03-2008, 2:19 PM
I would think that you would want to zero the unmagnified optic at a closer range. whatever you plan on using it at most often.

Jicko
11-03-2008, 2:45 PM
http://trijicon-inc.com/dmgnt_files/070305_ECOS_Manual.pdf
Here is the Op Manual for TA31ECOS, they recommend that the red-dot sight to be zero'ed @ 40meters.

And the center of the crosshair to be zero'ed @ 100meters.

I think most important thing is, to UNDERSTAND what these all means. Regarding the ACOG, zero'ing @ 100 is good since you can use the 300 line for your 25 POA/POI.

The red-dot is a little tricky since it sits so high up and have a huge distance from the red-dot sight to your bore. What you should do after you achieved your zero, is to put the data into JBM, and list out the whole trajactory with 5yds/meters increment from 0 - 100, then you can see and also plot, if necessary the effect of POA vs POI.

aplinker
11-03-2008, 5:53 PM
You definitely want the ACOG reticle zeroed at 100yds. All of the BDC is set based upon that zero.

A 40m zero on the red dot will mean you're withing probably 4" from 40m-250m.

Jicko is right, you need to understand why and what it all means.

Mark One
11-03-2008, 5:58 PM
Question,

I don't remember where I read this but I heard the Military makes their infintry site their weapons in at 25 yards. (Iron Sights)

I have a close indoor 25 yard range near me so should I just use that to zero in my rifle? Or wait for the outdoor 100+ range? Basically what I am asking is will a rifle sited in at 25 yard keep its POI at 100 yards?

dwa
11-03-2008, 6:00 PM
Question,

I don't remember where I read this but I heard the Military makes their infintry site their weapons in at 25 yards. (Iron Sights)

I have a close indoor 25 yard range near me so should I just use that to zero in my rifle? Or wait for the outdoor 100+ range? Basically what I am asking is will a rifle sited in at 25 yard keep its POI at 100 yards?

army zeros m4/m16 at 25m i belive the marines do it at 36m and i dont know if the airforce even knows theyre supposed to zero their weapons :)

aplinker
11-03-2008, 6:34 PM
Rifle zeroes have been changing.

I would recommend the Improved Battle Zero.

Here's some excellent reference material:
http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw

Jicko
11-03-2008, 6:54 PM
I don't remember where I read this but I heard the Military makes their infintry site their weapons in at 25 yards. (Iron Sights)

I have a close indoor 25 yard range near me so should I just use that to zero in my rifle? Or wait for the outdoor 100+ range? Basically what I am asking is will a rifle sited in at 25 yard keep its POI at 100 yards?

IF you read the link I last post in "details", the POI of 25m = POI of 300m. So if you zero your rifle to 25m, that is equal to zero'ing @ 300m, that's why some "military" branch choose to do it that way. Most of us may want otherwise.

Actually on page 18 of the PDF, if you have access to a 25yds/m range, you can use the 300yds/m markings on the ACOG as POA/POI. Then that is VERY close to a 100yds/m zero.

biko
11-03-2008, 8:06 PM
You definitely want the ACOG reticle zeroed at 100yds. All of the BDC is set based upon that zero.

A 40m zero on the red dot will mean you're withing probably 4" from 40m-250m.

Jicko is right, you need to understand why and what it all means.

Thanks for everyone's input.

That makes sense... I hadn't considered the BDC was calibrated specifically.

I do understand the "why". That's why I wanted a 50/200 zero.