I recently put the .308 into a McMillan HTG stock. I wanted to get the 3.5-10x40 M1 as low as possible while also having a sloped base, in order to maximize useable internal elevation adjustment.
Decided to try the Burris Signature dual-dovetail rings/bases. Not bad. Reasonably strong setup. About as low as reasonably possible. It's pretty clean looking. I can like it.
These rings came with two sets of .10" eccentric inserts, so I set them up fore and aft, to get approx 20 moa slope. Ring tops are 4-screw. Rings and bases are matte finished. The pic caught a litle glare from the camera flash, and oil on the bases.
Setting up the slope angle via the inserts is very simple.
The rings come with a set of neutral inserts in place, which consist of two halves for each ring. An upper half and a lower half.
Also included in the package are four more halves. Two marked +.01, and two marked -.01.
All I did was replace the lower half in the front ring with a -.01 insert to drop the front of the scope, and replaced the lower half of the rear ring with a +.01 insert to elevate the rear of the scope.
That gives you a slope of .02" in a distance of 3.75" (ring spacing). That works out to 19.2" at 100 yards, by my math. On a long action it would be somewhat less, as the ring spacing will be a little further apart.
Here's another perspective,
