If you have a weapon mounted light, practice shooting with it mounted -- the gun handles differently.  It also allows you to see if the light stays mounted under recoil.  A friend of mine borrowed my light to see if he liked it.  Third shot and the light went for the deck -- not good.   
Ditto!  And, uh, ditto.  That was with #4 shot too that my light fell off.  It's now more appropriately seated.
Anyway, it's always a great idea to check the placement/security of a gun-mounted light.  Which is, itself, a topic of great debate, mainly, don't point a gun at something you don't intend to shoot, which you have to do by default if the light is ON the gun.