There is something to be said for commonality of equipment. That something is this: "Keep all the widgits the same from one weapon to the next, and maybe you won't forget how to work them when the SHTF." Towards that end, The Old Fat Man has caused his defensive shotgun to grow a flashlight pretty much in exactly the same place as his carbine. Not only is it in the same place, but it works the same and feels the same. Of course, it took different hardware, but in today's age of rail that's not a big deal.
It began with the rail mount, and this one is a LaserLyte unit made for 12 gauge shotguns. It clamps to the magazine tube, and so far I have not managed to budge it after several large handfuls of heavy buckshot through the weapon. The mount provides three rail positions; right, left, and underneath the tube. After that, what more can one say about it? It's simple, reasonably priced, easy to put on, and tough enough to do the job. Next, the flashlight and mount. In this case, both are Fenix made, and procured from Amazon.com. The mount is a well thought out rig that allows for flashlights of different diameters to be fitted. The center bolt tightens the mount to the light, while the outer bolts tighten the mount to the rail.
Mounting the flashlight to the rail mount is nothing more daunting than sliding it in and tightening the bolt! If the flashlights bezel and cap are too big to slide into the mount, simply unscrew one and then slide the flashlight in.... reassembling the light after it's in place. I found it best to attach the mount to the rail first, and then install the light in it. All three bolts are then tightened with the supplied tool. The rig fits solidly.... VERY solidly... and does not move at all under heavy recoil. In use, the flashlight's rear activation button lines up very nicely to the shooters thumb as the fore hand controls the slide. I have no issue controlling the light this way on either shotgun or carbine.
Remote switches are available, and can be screwed on to replace the flashlight's tail cap, with a short cord and a pressure switch mounted to the slide. These work...... but....(and it's a BIG but)..... I have problems with cords and wires hanging off the side of a weapon. Biggest of these is the 100% surety that I will rip it the hell off at the very first opportunity. There is no 'chance' involved here. I KNOW what will happen.
No..... The Fat Man will stay with a simple button to turn his light on. Even then, a back up flashlight will be at hand..... just in case I knock the weapon light clean off it's mount by 'accident'.
So now all three home defense weapons have lights mounted on them. Pistol, Carbine, and shotgun. BRIGHT lights. BLINDINGLY bright lights.... and I practice with them often. Next, I will be mounting one on the S&W 15-22 play/training rifle.... and increasing the commonality factor just that much more.