I just picked one up for my new 20 ga 11-87, I will be testing it out in a few days and I'll let you know. (seems very solid). I'll be using a Burris fastfire ii with it. The mount only let's you mount the fastfire in the middle of the whole rail so the ff ii will sit on the vent rib not back over the receiver if that helps. I may cut the part over the receiver off as I won't need it.
Happy hunting
Erik