PRI forearm rails

I assumed they would be totally modular -- i.e. that you could place the 3", 4", 5.5" or 8.5" essentially anywhere.

That doesn't seem to be the case though. There are holes in the right general area, but it doesn't quite line up. Is there any documentation as to what exactly fits where?

I'd have preferred a 3" for my VFG & light, but apparently they only fit on the muzzle-end of the forearm.

http://homepage.mac.com/michael_aos/...I/IMG_5811.jpg

I removed the 3" rail that houses the sling-adapter since this picture was taken and replaced it with just a stud.

Mike