I've got the 4.5x14x40 AO...it's a very nice scope. It's sitting on my Savage Model 12 .223 right now, but I've had it on an AR for a while.
The only complaint I have about Nikon scopes is they are Looooonnnnnngggggg
...several inches longer for the same amount of magnifcation than some other scopes, like Burris.
Out of curiosity, what price are you looking at? If it's at all close to $300, you might want to look at the Weaver Grand Slam in 6x20x40. I've got one of those as well, and I like it better than the Nikon. They go for around $335, so there's not that much difference pricewise between the two, I don't think.
I don't think you'll regret the Buckmaster, personally. There seems to be 2 schools of thought around here...some folks like them than other scopes costing significantly more, others are kinda meh about them. I like them, myself.
EDIT...for that kind of money, I'd get the Grand Slam.