I soaked mine in 50/50 mix of acetone and ATF overnight, then put it in my viper as tight as I could with tape on the barrel. Used a breaker bar and the threads broke free fairly easily.
I had one that I had to do a relief cut on as well. I tried everything to get that barrel off and it just refused. Can't remember exactly, but I used either a dremel cut off wheel or hacksaw and spent 5 minutes to make the cut and the barrel basically spun off by hand after that.
Put a casserole in and we'll all be over after the kids go to bed.
I'd rawdog it at this point, get the action so close the the vise you think it will scratch it, and torque the top 2 bolts on the vise so hard it bends the plate.
make sure you don’t over tighten the action vise and put too much pressure on the threads i did that and struggled big time ever since i figured that out they usually come off somewhat easy
Patriot Valley Arms just does a relief cut to take off factory Tikka barrels. If you don't care about the barrel's resale anyway that seems like the simplest option.