It depends on how heavy your barrel is. They will work on a varmint weight or even a little heavier. It might be close on a huge bull barrel. This is assuming a normal height one piece pic rail.
I would not recommend the Leupold QRW for a NF scopes. Will they do the job? For the most part yes but they will come loose. I use a set on a Styer hunting rifle I have and they come loose.