If you want a shotgun for defensive use, you would be hard pressed to beat the Beretta 1301. If you want an optic to use on that shotgun, you would be hard pressed to beat an Aimpoint Micro. It looks like Aridus Industries has a plan to let you do just that.
They gave us a sneak peek at a prototype optic mount for the Beretta 1301. It allows the user to mount an Aimpoint Micro and uses what appears to be an XS Sight Systems rear ghost ring assembly to co-witness with the Aimpoint. The prototype is machined from 6061 aluminum and obviously left in the raw. Aridus Industries states that the design still need some tweaking and there will likely be changes before it is offered for sale.
Learn more: AridusIndustries.com
Do this for the Benelli M4 and just replace the pic rail; I’d say it beats the Beretta.