Bobster
.30-06
I think the riser is a good idea if it helps you line up the dot. The only red dot I had on a shotgun was a Tri-Star (Turkish) Semi 12ga with tactical pistol grip stock so the comb may have been different. Conveniently, the red dot co-witnessed with the factory sights. I tend to keep both eyes open when using a red dot, I think? I don't have one mounted right now to check...