You can use an adapter to hold the light in your shell carrier, although it's kind of annoying, because it a cast a shadow and the light's not in-line with the barrel...the Streamlight mount is the best for keeping it lined up with the barrel (just remove the magazine cap, put the streamlight holder on, and screw it back on), that way you can basically use your light to aim, instead of your bead. If weather's a concern, I've used my Surefire's (G-2's) while caving in Iceland (10 degrees/35-50mph winds)...and they never gave me a problem...so 10-20 degrees probably won't effect 'em...and, when compared to my other flashlight's, Surefire's are sealed the tightest. I don't have one of the 9-Volt Handheld Surefires yet (I do have a 918FA on my Marine Magnum though), on my 870 express I use a G-2 ($36) with a P-61 for targeting (120 Lumens), and a G-2 with a P-60 and a red filter for "navigation" (so I can see where I'm going/ID my surroundings)...not a bad set-up. Given the colder temperatures though, I would go with the G-2/G-3 (Nitrolon) bodies as opposed to the 6-P/9-P (aluminum), as the G-Series will hold the heat a little better, and keep your light and batteries at a more reasonable temp. Nice for in the winter and you need to go out and blast some coyotes!!!