Putting an airgun scope on a 300 win mag? That's not gonna last long.
OP, Leupolds have come up in price since I last looked. Last I saw they were $250, a few bucks more than the Bushnell's you listed. They're over $300 now. If you can wait, I still think they're worth the money. Having recently plunked a cheap high-magnification scope on my 223 (for target shooting), the quality is poor compared to the Leupold I took off it. I'll offer it for resale because it's just fine for varmint hunting but I need a clearer sight to see my 2" target at 200 yards. If you need a scope quickly hopefully someone will chime in with more info. Otherwise I'd recommend going into a store and asking to have a look down the scopes for yourself. Sight across the store and check clarity and brightness. Ask the opinion of the counter man or woman "Given a $250 budget, what would you choose and why?".
And don't be afraid to say "Thank you for your time" and walk away to think about it.