Ullie is right [stunner, I know] - I own the Leupold VX III 1.5-5 x 20 rifle scope and it probably isn't enough magnification out at 300 yards (I would go to 9x or 10x out that far) - at least for my eyes, and I have 20/15 vision with my prescription shooting glasses on....
The VX III 1.5-5 x 20 is great for fast target acquisition close in [100 to 200 yards] and it really works great in low light or twilight conditions. Lightweight, tough, lifetime guarantee, clear optics, wide field of view, large area eye box so you don't get "scoped" (impact cut) under heavy recoil [happens to rookies a lot], and great eye relief at lower magnification settings. Hard to beat combination on a carbine. I really like mine - and it works for hunting or tactical use, as Ullie also notes. But I think you need a more powerful scope once you pass ~250 yards....