In my opinion two "factory" rifles have made custom rifles a luxury instead of a need (for reasons that Larry and Jay pointed out; magazine length, twist rates, stock, high QC, triggers, fasteners, bedding, accuracy, etc.)
Light weight rifle - Barrett Fieldcraft
Sporter weight rifle - Seekins Havok
I've had many friends that aren't into rifles shoot one of my rigs and ask how to go about getting a custom. I always point them in the direction of Barrett or Seekins depending on their needs.
