I have a 3x9x50 Vari-x II on my 300 and a 2x7x33 vari-x II on my muzzleloader. At anything but the extreme ranges of the 3x9, the light gathering abilities between the two are not that substantal. At some point the ability of the human eye to gather and utilize the available light reaches a point of diminished returns. Unless you feel the need for a 50mm, "in my opinion" a 40mm will do the job.