Well, I've been meaning to turn my mossberg 500 from a skeet busting machine into a handy home defense gun. Problem is that the darn thing was just too long for me and I could never get it up to my shoulder let alone handle it in the hallways.
I want a folding stock (pending) but decided to throw a pistol grip on it. Why not, had it laying around for a while.
Then I thought about lighting. I lost the ability to use the sights with the pistol grip, so I want to be able to light up my target as well as get my point of aim. I tried a few different mounts down low but couldn't get anything the way i wanted. Eventually I settled on the top rail, and added some scope rings to hold the light. I used some paper to make a tight fit before getting everything nice and tight.
So far it's a nice poor man's tactical shotty. It's still too long so an 18.5" barrel is in the works.