The reason that Sako (Sock-O) and Tikka (Tee-ka) rifles’ bolts operate so smoothly is that the receiver raceways are broached instead of drilled, leaving no extra points of contact beyond the locking lugs.

If you’ve never worked a bolt on one of these fine Finnish rifles, go try one. Take your wallet with you. They’re also extremely accurate and have great adjustable triggers. (Required to shoot 1 MOA before being shipped.)