BigKracka, I use a Coast Products TX40 on both my 590A1 ans Olympic Arms AR. I like the Coast lights alot, and have a couple others too.
Keep in mind a light is for quick target ID and not illumination. Strobes intended for disorientation, but just as Brnd72 suggested it can be a target. Some folks go for specific traing with weapons lights.
As for the Coast, check out this thread! I have a short and cheesey music video at the end of the thread! Coast Products