Re: Millett LRS or Vortex Crossfire
Vortex makes great scopes, but their low end (like crossfire) seem to have more issues. I have had 2 of them and they worked fine, but several people have had issues with them. I would go with the Millet between the two. I have used a Mueller for over a year and it does the job as well, they have great warranty and customer service. I have returned one before and it was a fast turnaround with EXCELLENT service.
I would spend a little more and get a better scope, especially considering your son might shoot longer range. I shoot out past 600 with a 14x and it does fine, but I prefer something closer to 20-24 if possible.
I have several Nikons and love them, they also have longer eye relief. Also, the vortex viper is a special buy right now at $279 from cameraland, I bought one and it is good (it has 3" eye relief which is fine for most rifles but i prefer 4").
A used nikon buckmaster is usually around 200-225 range.