I have a busnell holo sight that I have mounted on my FAL. At 100yds it is shooting high, that should be normal? Second I have an AR with a rail systme (not the SIR), I am thinking really serious about an aimpoint or another bushnell/eotech. What is the mount I will need to get the proper elevation for Co-Witness? Right now just on the rail is too low. thanks

To answer this question properly we'd need to know a few things.

What is the height of the optic (center of the opic will do) to the center of the bore?

What is the range at which you zeroed at?

How high is it hitting over point of aim at 100yards?

Assuming you zeroed it at 25 yards then yes it will be hitting somewhat high at 100 yards. (figure about 3" HOB, then you'll be hitting in the 6-9" high range.

Speaking stricly for the AR w/ rail system.

An EOTech sight will mount directly to your flat-top or to your rail system (PROVIDED IT IS AT THE SAME LEVEL AS YOUR FLAT-TOP RAILS) and co-witness perfectly w/ your iron front and BUIS rear.

An Aimpoint ML/ML2 utilizing an ARMS #22M68 mount, needs a FULL-spacer to co-witness from the same places listed above. You can also use and Aimpoint (w/ same 22M68 mount) in conjunction w/ an ARMS #38 Swan sleeve, EX or Super-EX and a ML/ML2 and NO spacer for co-witness, (the ARMS #38 slide over your flat-top and contains a BUIS (ARMS #40).

Ya didn't state whether the AR is an A2 (carry handle) or A3/4 (flat-top), but hope this is some help, for A2 upper there's an ARMS #39A2 handle mount that will co-witness w/ the ML/ML2 (on ARMS #22M68) for that application too.

Mike