Thought I'd share my solution to adding a light to my new toy. It's so simple I'm sure many have done something similar, but I did not see anything on the web so here goes...
I used a Surefire G2 because one, it's my favorite light and two, it's cheap and lightweight. Since the rifle is my BOB gun, I figured if the light got damaged I would have a replacement on me already anyway. Redundancy is good sometimes.
I started by taking an old cheap Russian scope ring I got with a $30.00 scope out of SGN years ago. They were so roughly made and bulky that I would never use them for a good scope, but now am glad I didn't get rid of them.
I cut the base of the ring down to make a flat sureface on the mill, made a slight radius with an air grinder (hacksaw & files will work also), and then tapped the base in two places for 6-32 socket head screws.
Drilled two 1/4" holes in the handguard corresponding to the tapped holes in ring, and secured with the back plate (a small scrap of "banding" used to band loads of wood for shipping that is spring steel and bends to the contour of the guard nicely), washers will work also.
Now I have a close mounted light that is easy to actuate with the knuckle of my thumb without loosing a solid grip on the gun.
PS. The keyring on the tailcap is a trick I found to turn the G2 into a momentary only light. It's a 1" OD ring that can be found at any key cutting store and works great.