I did a search and didn't seem to find any info on which part of the SIR rail to mount an ML2.  I'd like to have an idea on which rail to start with before I decide what is comfortable.  Any info and pics are welcome.

Anywhere you'd like.  

General wisdom is the farther forward, the better.  Personsally, I like the rear of the Aimpoint at the front of the lower receiver.

I like mine at the end of the reciever over-hanging the delta ring.

Its far enough forward for my eyes that Im not dealing with the "looking through a tube" effect with both eyes open, yet the rifle maintains some sort of balanced feel to it.

Put it as far forward as it'll fit.  Rail or gooseneck is better than the receiver.  Enhances target acquisition and transition as it moves away from the eye.  Most dot "distortion" is from being too close with the sight set too bright.

Whatever works best for you, that's why there's more than one slot.  I use a ARMS #39A2Plus and have to flex the front sight cover to clear the front sight post.  Covers flip down to 5 o'clock in front and flat down to 6 o'clock at the rear.

-- Chuck

I'm with Lumpy on this one.  I have my ML2 mounted on an ARMS 22M68 and attached to my flattop upper so the mount just starts to hang over the dleta ring.  A lot of guys say it should be mounted even farther forward, but I like my setup a lot.

It also have a lot to do with rifle balance, this is just some thing you have to experience with. you have to balance the front end heavy with field of view.  A front heavy weapon can ocause over swing on fast multiple target engagement.  mounting an optic is personal, you got to go to a range and test the difference.  it will take a couple of trip until you find your perfect spot.  

Hope this helps.