This is one of the neatest i have seen, mounted forward, but arent we still in a situation of contradiction? Double rifles with express sights are designed for being mounted like a shotgun - cheek weld, sights right on from the proper fit. So even with this shown set up the dot would be maybe 20mm above that 'perfect' line of sight. I am aware that, especially with O/U doubles some are specifically stocked for a scope and have a raised cheek piece. But then the express sights can no longer be 'perfect'. So do you just accept a compromise, or shoot open sights and be done with it?