I found the below data on the below listed M3 Xenon Illuminate shooting light... It has 90 Lumen's and the distance for it use is 25 meters.
25 meters equates to 27.34 yards... So to illuminate something at 100 yards you would need at least a light with 360 Lumen's??
However one has to take into consideration the full moon, new moon, overcast etc etc etc...At best this particular lumen's on this light would make it excellent for the shotgunner...Since it will illuminate to 27.34 yards and a bit beyond..
Item Description
The M3 Xenon Illuminator, by Insight Technologies, has been the gold standard in weapon mounted illuminators since it was first introduced in 1998. With a reputation for rugged reliability, the M3 can be found in more law enforcement and personal defense holsters today than any other weapon light on the market.
•Mounted weapon light
•Battery Type: 3V 123 lithium
•Battery Quantity: 2
•Lamp Type: Tungsten halogen, xenon filled
•Run Time: 60 minutes continuous
•Peak Output: 90+ Lumens
•Range: 25 meters
•Mounts easily without the aid of tools
•Slide-Lock interface
•Designed to fit most pistols
•Ambidextrous rocker switch located on the removable backplate
•Dimensions: 3.4" L x 1.57" W x 1.52" H
•Weight: 3.3oz with batteries