I suspect that sights that look like M1 or M1A sights are not available in a rail mount, but I could be wrong.
There are rail mount peep sights that function just like the M1 sights that are available for the AR-15 but their markings are generally set for 223 Remington ammunition.
I am sure that similar sights are available for the AR-10 platform which is available in 308 Winchester. Windage and elevation would function just like the M1 sights, the rear sight would be a peep sight like the M1's sight. It jus would not look like an M1 sight.
Maybe someone familiar with the AR platform will chime in.
Hope this helps.