i use a light thats mounted on my hat with a belt mounted batery.i tip the hat slightly to the left(i shoot right handed)so when i'm aiming the gun the light is following the barrel and right on to there eyes.i have a barrel clip for my light but don't use it to often becouse it requires me to move the whole gun around trying to pick the eyes.this is an incredible amount of movment that i can't live with.although i will admit that once there eyes are in view the light on the gun is alot easyer.there for sometime i will have the barrel clip on but keep the light on my head untill a predator is spoted.then if its possible i will put the light on the barrel.if your putting one on your scope you will find its eayest to put the stock of the gun on top of your shoulder with the trigger gaurd against your shoulder and scan looking down the side of the gun or scope.its very uncomfortable to scan looking thru the scope,after awhile it realy gets to ya.try it this way and when something is spotted then ease the gun/rifle to your shoulder and look thru the scope.my light is for when i'm using shotgun,can't use the rifle with lights.