Thanks for all of the pictures and replies- it has helped me in forming an educated decision.
I'm likely going to buy a nordic components mag extension support clamp with rail to mount the flashlight upon. Are these as sturdy as they look??? I've owned nordic components products in the past, and would buy again without hesitation.
I've chosen this because
1). I am waiting for a "real" 1913 rail from Kip (like everyone else)-so no shell-holder/rail combo with fake integral 1913 system. I have an eotech that isn't being used for Kip's rail (when it arrives).
2). I don't want a flashlight in my way on the handguard (so B&T or surefire are out)- besides, they are sooo expensive and what would I do with all of that mounting room (practically speaking).
3). As for the shell holder, I have an FN SLP that I use for 3 gun competition- A while back I purchased a "3 gun gear" shell holder that sits on the left side of the receiver (with an adhesive and strong velcro). Never had any problems with this equipment- so I'll probably get that shell holder for my M4.
I figure the likelihood of having to reload (this gun is a home defense only shotgun) is pretty slim- besides, I will be putting an extended mag. tube from Kip on the M4 when it arrives.
Please let me know if you have any constructive input related to this set-up. I realize it may not be as tacticool as some of the guns I see on here- but I'm trying to keep it simple and effective as this gun could save my or my family's lives some day.