I really don't know anything about the quality of the Nikon Buckmaster...
Except,I can give you this advice,if its made in China stay away from it....[:'(]
I'm more curious as to why you want something like this 4.5x14x40mm on your .270..
I'm guessing this gun/scope combo won't be used on varmits.....
But if it is, I'd still recommend a different scope size and power..
First off (for me personally)The lowest mag setting is a little on the high side for shooting biggame at close range..
Alot of people don't mind it, (they have theirs set on anywhere from 4x to 6 power) but there is alot of advantages on having a smaller magnifiaction than the one your asking about on your scpoe..
The most obvious one, field of view...I can see the reaction of the animal if I hit it,
and I can see the the dustoff in front behind to the side if I was to ever miss.......
I also like the fact that I can can see twigs and branches that otherwise would be obstructed right out of view with a higher power mag scope.....
As you turn up the mag, the image will be bigger but and it will also become noticeably dimmer once you exced the 5mm exit pupil..
With a 40mm objective lens, theoritically this will be at 8 power give or take...
This 8 power mag is maybe (it varies from 6X to 10X )what you'd want for shooting big game out to 500 yrds but basically anything past 10 power will not be used at all with a 40mmit just won't be bright enough to make an ethical shot at long range...
Not to mention good luck even finding the target at close range....
There are better alternitive scopes to choose from.....
If you want to stay with the 40mm lens.......
I personally choose a variable mag a litttle smaller ,something like 3x9x40mm or 2.5x10 x40mm my personal favorite 1.5x6......
If higher Magnification (eg. 12 -14X)is what you want, go with a scope that has a bigger objective lens..