Look into the “SASS” (Semi Auto Sniper System) models of the AR10 from various manufacturers.
If legal in your jurisdiction, get a suppressor.
FWIW: quality equipment ain’t cheap. If you have to pull the trigger, and what you expect doesn’t happen, you’ll wish you’d spent more (at least for another second, then you won’t care - ever).
I want to keep it short in length for use in urban areas.