A is overtravel, B is pull weight, and C is sear engagement ("creep"). Adjust A by turning it in until it stops, cock the action and pull the trigger. While simultaneously applying pressure to the trigger, back out the setscrew until the trigger just fires, then turn the setscrew out an additional 1/2 to 3/4 turn to ensure you always have sufficient clearance for the sear to trip. Adjust B to the desired pull weight, but not too light such that the trigger can fire from the rifle being jarred. Test afterward by trying to slam fire the action. First put the safety on, squeeze the trigger, release the trigger and flick the safety off. It should not fire. Then work the bolt vigorously with the safety off, slamming the bolt closed hard. Again, it shouldn't fire. Finally, with the action in the stock, bump the buttpad against the floor smartly with the action cocked and safety off. If it still doesn't fire after these three tests, your adjusted pull weight is probably safe. Once you have the trigger to the desired pull weight, tighten the jam nut back against the housing. IMO, a good big game hunting trigger weight is no less than about 2 lbs. A 2 lever trigger design like the Sako is not designed for a safe pull weight much lighter than that.
I would avoid adjusting sear engagement unless you have excess objectionable creep. To reduce sear engagement (amount of creep), turn the setscrew until the cocked action fires, then back out about 1 additional turn or so in order to insure you have sufficient sear engagement for safety. Be very careful with this adjustment -- too little sear engagement is even more dangerous than a pull weight that is too light for the trigger design. If you do adjust it, do so before you adjust pull weight and do the slam fire tests to verify safety. Of course, it goes without saying that you should verify the rifle is unloaded before adjusting the trigger and/or testing your adjustments for safety. Once you get all adjustments to your liking, it's a good idea to put Lock-tite, some type of enamel sealer, silicone, or other thread locking compound on the setscrews to prevent them from moving.
Adjusting the trigger isn't difficult, but the consequences for making mistakes can be deadly, so I would suggest that unless you are very experienced with working on triggers, leave trigger adjustments to a qualified gunsmith. It won't cost much, and it's best to always err on the side of safety when dealing with a gun's fire control system.
Edited by RifleDude