I am trying to site in a new Bushmaster carbine and the manual says to zero at 6/3 plus "one click" (for 25m).  I take that to mean one positive click up from 6/3 and not some other point.  Is this correct.  Also, should the adjustment wheel bottom out at 6/3 or should you be able to go down past 6/3?  Thanks in advance for any help.

Correct, there should be a mark (a small z) where the click is.



There may be two or three clicks below 6/3.



You're welcome

[url]http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw[/url]
This should answer all your questions.

Green 18,
I believe I want to sight mine in again using the Improved Battlesight Zero.  (I will never shoot further than 200M, will usually shoot at just 100 yds.)  I had had to lower the blade front sight on my XM15-E2s significantly (as in practically as low as it could go.)  Before I try LTC Santose's method, should I raise the front sight back up to flush?

green18,

I used the IBZ and zeroed the rifle at 50 yards with the small aperture and 6/3-2 clicks.  I understood this to mean it has a zero of 200m with these settings.

Is this theory correct:  

IBZ  states 200m zero with 6/3-2 and small aperture.  

IBZ also states if patrolling, 6/3 and large aperture is same trajectory and 200m zero.

USMC 300m battlesight zero also states that 6/3 and large aperture is a 200m zero; however, this zero is established with 6/3+1 and small aperture at 25m.

Does this mean that:
1. At "X" yards (between 0 and 200), 6/3-2 and small aperture will have same trajectory and point of impact as 6/3 and large aperture?
2. If zeroed per IBZ, the sights should already give a 25m zero with 6/3+1 and small aperture.

Are these ideas correct or is my thinkin' "way off base"?  Thanks.

G22inSC:

Bad form to post the same question in two forums. 1 Demerit [;)]

The 25M zero you speak of has been completely  discredited.  The Marines no longer use it (they use a 36y method instead).  If you go back to teh site where the IBSZ is posted you can find the new Marine 36Y method posted and you can find charts showing how the different zero methods compare (based on round use and barrel length).  Looking at the charts you can see why the IBSZ is superior to the other methods, and why the old 25M method isn't worth the paper its printed on.

Will remember about the double post.  

In regards to my previous questions, will the IBZ and the New Marine 300 Meter Battlesight Zero produce the same results and points of impact?

Didn't realize the USMC 300m zero was that far off.  Thanks.

A rifle zeroed with the IBSZ, using the small aperture, with the dial set to '3' will hit to the same point of impact as the same rifle, using the small aperture, zeroed at 36yards (the 'new' USMC zero).

[i]I say 'new' to differentiate from the 'old' 25M zero shown in the -10; some Marines have been using the 36y zero for quite some time.[/i]