OK, now I'm even more confused. By my thinking if the gun is shooting low, I need a thicker shim to drop my eye (i.e. rear sight) in order raise the front sight. I found the below post in one of the many searches I've done and it seems to indicate the opposite approach. Can anyone help explain that for me? Will using a C shim actually raise the POI vs. a D?
If the gun shoots low, then you need a thinner shim. If your high, use a thicker shim. What most shooters want is a 60/40 pattern. Where 60% of your pattern is high and 40% is lower. Be sure with the locking plate (the part thats heavy and goes in the stock) to use the corresponding plate that matches the shim that you use: 55mm shim=55mm locking plate.
edited to remove link to post titled M2 Shims, how to adjust it?, don't have enough posts...