I have a Bushmaster 20" A3 and want to set a completely zero my rifle from scratch.  

According to my USMC Rifle Marksmanship guide, the rear sight elevation knob should be first bottomed out when initially zeroing your rifle and when bottomed out should be 3 clicks counterclockwise from the 6/3 marking.  It then says if it's not 3 clicks counterclockwise from 6/3 when the base is bottomed out, it needs to be adjusted by a qualified armorer.  Then you need to rotate clockwise until 6/3 is aligned with the index mark.

Here is a picture I just took of my rear sight base completely bottomed out, and as you can see, it's not aligned properly like the USMC Rifle Marksmanship Manual states it should be:



What should I do?  Where should my elevation knob be set for what i'm trying to do?  The Rifle Marksmanship Manual is specifically for an A2 and I have an A3 so i'm not sure if that makes any difference.

I did read that some Bushmasters have out of spec rear sights/carry handles that are problematic, do I have one of those?

Thanks a lot

Quoted: I did read that some Bushmasters have out of spec rear sights/carry handles that are problematic, do I have one of those?

Nope.  Your sight is normal.  It just needs to be adjusted. LTC Santose explains how to do that in his Improved Battle Sight article.  You don't have to use his method of zeroing the rifle if you don't want to, but the adjustment of the elevation wheel is the same for any method

Quoted: Quoted: I did read that some Bushmasters have out of spec rear sights/carry handles that are problematic, do I have one of those? Nope.  Your sight is normal.  It just needs to be adjusted. LTC Santose explains how to do that in his Improved Battle Sight article.  You don't have to use his method of zeroing the rifle if you don't want to, but the adjustment of the elevation wheel is the same for any method

I just adjusted it according to that and it now it's aligned perfectly, thanks.