They shouldn't be defective to begin with.
I purchased 2 Burris FFII's after directly comparing them to Leupolds costing much more.
I am curious as to how you compared them to the Leupolds. I've got a Burris FFII and, after hours at the range and in the field, I do not think that the FFII's are optically better than any of my Leupolds. Honestly, I am happy with the Burris for the money and for what I use it for, but, as far as quality of construction goes, the windage and elevation adjustments have given me problems since I took it out of the box. They are hard to adjust, get hung up and have to be tapped to actually break free, and they are not as accurate to the 1/4 MOA as any of my Leupolds.
Most Burris retailers have a wood gunstock with a rubber scopemount that allows you to stack two scopes, one above the other so you can hold the stock like you were shooting and shift your eye up and down to compare the scoped directly.
I was 'aiming' outside the windows of the shop and looking into a dark room across the street.
Lupold vs Burris FFII. I could see more detail and the room looked brighter thru the Burris.
It was a very direct and objective experiment.
I handed it to my bro in law and didn't influence his choice, just said 'which one do you think is clearer and brighter?'
He didn't hesitate....Burris.
My FFII's live on some pretty intense rifles....6.5lb 300WSM.
Shoots very well, adjusts accurately when I need it to(not often, just load development)
I am convinced the competition has caught and passed Leupold.