Sako factory triggers (particularyly the older ones) can normally be adjusted down to a safe +/- 4lb pull with minimal effort. If your trigger is hard and gritty I suggest pulling it,soaking it overnight. and using some pressurized air to blow it clean in an attempt to remove any built up grease, lubricant, and foreign matter. Once this is down, try the adjustments again.
If that doesn't work, try to locate an experienced gunsmith who has expereince disassembling triggers to diagnose and cure your your problem. In my area this work normally runs about $50. If all else fails, Timney makes a good crisp drop in trigger that retails for around $125-130 when they can be found.