Bolt timing on turnbolt actions is usually engineered into the design. USUALLY, needing no alteration, unless an aftermarket cocking piece and/or striker assembly is installed, or in the case of post '64 Winchesters, some Ruger 77's show either poor engineering or poor quality control in manufacturing. As other posters have noted, "timing" sequences should accomplish 3 simple tasks.
1. after a cartridge is fired, the first few degrees of bolt rotation initiates primary extraction, either with the bolt handle root camming on the rear receiver bridge or and inclined plane milled into the bolt lug recesses in the front bridge.
2. just a few degrees after primary extraction is achieved, the bolt sleeve cam begins to lift the cocking piece/striker assy. this retracts the firing pin nose .080 thousandths or so to avoid breaking the firing pin because of an off center primer strike, as the bolt rotates.
2a. now remains the rest of the bolt movement, of no interest to the discussion of timing, completion of cocking (Cock on open designs), secondary extraction, ejection, feeding and chambering
3. now we are "in battery" bolt handle closed, cartridge chambered, cocking piece held rearward with the sear engaged. As mentioned by a poster above with bolt handle "twitch", the third job of timing must be met. a: locking lugs fully engaged b: bolt handle firmly seated on the action rail or whatever register point is designed c, the striker hump PERFECTLY aligned with the longitudinal slot milled in cocking piece. In the perfect world, the striker is free to travel forward without even touching the sides of the slot. Mauser and Mannlicher are about the only actions you see with no bolt twitch. Some commercial actions will display a false twitch, which is caused by the striker hitting the cocking piece long, milliseconds, after the bullet has exited the muzzle. This can usually be detected with a little Dy-kem or a magic marker.
Hope this helps the OP, just my opinion.
