An ACOG will NOT fit on to an EBR. There is no rail mount close enough to the shooter that would accommodate an Acog.
Reference:
Look at where the closest available rail real estate is that could accommodate an ACOG. The ACOG eye relief is no more than 2 inches.
The only way you can get your eye close enough to the ACOG is if you hunker down with your cheek up against the ejection port, and I guarantee you that won't be a comfortable position.