I'm considering a variable power, something in the the neighborhood of 6x to 24x and I don't want to go any bigger than 40mm. The gun is strictly for target shooting with the goal of maintaining the tightest group I can muster with factory ammo. My local range only reaches out to 200 yds, so that will be the longest shot for the time being. Any suggestions would be appreciated!! What do you guys think of target knobs?? THANKS!