Bushmaster M4 25 yard zero


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jayp
March 8, 2008, 10:58 PM
I'm gonna take it out for the second shooting session tomorrow. Just wanted to double check if I have it set up correctly for a 25 meter zero. I've got the detachable carry handle.

Windage: Set the knob so the sight matches up with the mark in the middle.

Elevation: Turn elevation knob all the way counterclockwise (which lowers it to the bottom) and then turn it up (clockwise) to the Z mark which is two clicks lower than the 6/3 mark. Windage adjustment at 25 yards as needed with the windage knob. Further elevation adjustments with the front sight post.

Does that sound right? What does "6/3" mean, anyway. Is that 300 meters out of 600 (i.e, is 600 meters the maximum range of adjustment?)

Thanks!

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rino451
March 8, 2008, 11:04 PM
6/3 means 600/300 meters. At it's lowers on 6/3 means that it's set for 300 meters. turn the elevation until 6/3 shows up again, it's set for 600 meters.

For A2 Sights:

In any case (for shooting or zeroing) you will need to have your A2 handle setup for the IBZ (-2 clicks below 8/3). Remember if you have a detachable carry handle your elevation adjustments are twice as fine so be sure to double all 'click' values (i.e. 2 clicks become 4 clicks). If you have already zeroed with the IBZ then to get a 25 YARD zero set your elevation wheel as indicated:

For 20"+ barreled rifles (or Dissapator style carbines) set the wheel to 4 +2 Clicks

For 16" (and less) carbines (short sight radius) set the wheel to 4 (400M setting)

From http://groups.msn.com/TheMarylandAR15ShootersSite/25yardzeroingmethod.msnw
If you are ZEROING your rifle (again not really recommended), after setting up your rear sight to bottom out at 8/3 -2 (or 6/3 -4) adjust the rear sight to the values indicated above. That is rifles will be set to 4 +2 clicks and carbines will be set to 4 (4 being the 400meter setting). Zero your rifle at 25 yards. All elevation adjustments for zeroing will be using the front sight. Once you are done the numbers on the elevation wheel should be correct. If you bottom the sight out (at 8/3 -2) you will have roughly the 50y/200M zero of the IBZ.

Note these sight settings were discovered using M193 (specifically Winchester Q3131A) at 500' ASL and about 70 degrees. Using slower comercial .223 may produce different results for zeroing, but should be good enought for shooting/plinking/qualifying at 25 yards.

jayp
March 8, 2008, 11:41 PM
6/3 means 600/300 meters. At it's lowers on 6/3 means that it's set for 300 meters. turn the elevation until 6/3 shows up again, it's set for 600 meters.

Thanks, it wasn't clear to me what the notation meant. So, when the sight is is it's lowest most position, it should be bottomed out on 6/3, which means zeroed for 300 meters, and one full rotation is zero for 600 meters?

On my Bushmaster M4, two clicks from bottom 6/3 there is a Z on the wheel. That is what I understand to be where the wheel should be when firing at 25 meters for the 300 meter zero.

DANGERRUSS
March 9, 2008, 01:39 AM
[HTML][/HTMThanks, it wasn't clear to me what the notation meant. So, when the sight is is it's lowest most position, it should be bottomed out on 6/3, which means zeroed for 300 meters, and one full rotation is zero for 600 meters?

On my Bushmaster M4, two clicks from bottom 6/3 there is a Z on the wheel. That is what I understand to be where the wheel should be when firing at 25 meters for the 300 meter zero.

L]

yes that is where you want to be for a 25 meter sight in.

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