The good news is, once you correct the problem your groups will shrink. If headspace is ok I’d strip the bolt and clean any debris out and lightly lubricate it. Look for a cracked spring, bent firing pin, bent cocking piece and spray it out over clean paper towels to see if a primer was punched before you had the gun and left a small metal disk in the bolt. If the gun is over 10 years old I’d replace the firing pin spring. Since you’re having problems I’d probably replace the spring anyway so you know that’s not it. Look for weird metal to metal rub marks and make sure the trigger retracts from the cocking piece and isn’t dragging. If decocking a bare bolt isn’t something your comfortable with, firing pin stick out is easy enough to estimate with a cleaning rod down the muzzle and flat faced brass jag - do not dry fire onto the cleaning rod, but let the cocking piece down slowly and compare the stick out. I have no idea what is common with Tikka but it’s probably more than .050” and less than .075”. If you feel more comfortable with an actual number, add a paper binding clip to the cleaning rod when cocked, uncock it and use feeler gauges to measure the gap between muzzle and clip.