When I was going to Texas to Hunt pigs a few years back I tired out a few different light mounts. Pic rail, scope clamp and the magnetic. I ended up using the scope clamp version as it gave the best results using a scope. With open sights I would have gone with the Pic rail. The two magnetic mounts I tried were not strong enough to hold a light in place when rapidly swinging the gun. If there had been a wider piece of metal to put the magnet on it might have worked but with the gun I was using there wasn't enough purchase.
Mine came with the light setup but it looks similar to this one. Having the beam of the light directly above the scope and just behind the Objective lense made it very easy to see the game looking through the scope.