I have a Bushmaster XM-15, with the A3 upper.  I recently ordered a Larue fixed BUIS.  I plan to take off the carry handle, and put on the BUIS as my primary site, until I get some optics.  I read over the IBZ instructions at MDAR15.com.  However, the Larue BUIS isn't adjustable for  elevation.  Can I still get it zeroed in properly with just the front site?  Any thing I should be aware of that I'm not thinking about?

Also, I read that there were problems with Bushmaster front site posts being to short.  Do I still need to get the taller (.040) front site post to use with my Larue BUIS?

One last thing.  The range I go to would only allow me three choices for distance to use when zeroing in (45 yards, 100 yards, 200 yards).  Which distance should I use, and what will be the elevation difference?

Sorry for all the questions, and thanks for your help.


Robert

Quoted: I have a Bushmaster XM-15, with the A3 upper.  I recently ordered a Larue fixed BUIS.  I plan to take off the carry handle, and put on the BUIS as my primary site, until I get some optics.  I read over the IBZ instructions at MDAR15.com.  However, the Larue BUIS isn't adjustable for  elevation.  Can I still get it zeroed in properly with just the front site?  Any thing I should be aware of that I'm not thinking about? Yes, you can still get it zeroed. Also, I read that there were problems with Bushmaster front site posts being to short.  Do I still need to get the taller (.040) front site post to use with my Larue BUIS?There's a good possibility.  I had to go to the taller sight. One last thing.  The range I go to would only allow me three choices for distance to use when zeroing in (45 yards, 100 yards, 200 yards).  Which distance should I use, and what will be the elevation difference? I would suggest 45.  Use the small aperture while zeroing. Sorry for all the questions, and thanks for your help. Robert

If you have access to a 100 yard range, then put your targets out half way and do 50 yards, which is the preferred.

Check out The Maryland AR15 Shooters Site, they have a section on how to sight in with an A1 rear sight. (LaRue)