How critical is having an adjustable objective on a varmint scope? All my current varmint rifles have AO's and I'm looking at a Leupold VX-II 4-12x50mm ,Part No. 58250 for a 223 Ruger V/T I just bought.I'd imagine 90%+ of the shots will be 300 yards or less with the 223,mostly groundhawgs.