I agree with you Hawk. I have a light mounted on my Remington 870 12 gauge. However my P226 with 18 round mag does not have an accessory rail. I also have a handheld Thrunite light on the night table.
But...train yourself if the light switch is anywhere close to the trigger. Found this interesting article regarding accidental shooting attributed to attempted light engagement.
http://www.denverpost.com/news/ci_25921024/gun-mounted-flashlights-linked-accidental-shootings