I recently acquired my first AR15. Along with it, a Troy folding rear sight and Vortex SPARC red dot. My thinking is that the zeroing process would be best achieved at an indoor range. If this is true, do you have recommendations of where I might go in the Hillsboro/Beaverton/Portland area? Maybe I can do this outdoors. If so, what will I need to bring/construct for stabilization and accuracy? Thanks so much for the help.