The problem is that the barrel lenght and power needed for sniping pretty much kills the CQB option. It's one or the other.
How about you pick a gun like the SR16 and keep it simple for now? Then you have a gun that is pretty much useable in many settings. Go for sniping when you have money for a second gun that you can tweak to your needs.
It's never a good idea to buy, or build, a specialized for your first gun. You limit yourself too much.
PS, get age-verified.