Thought this might help someone down the road. Last year I picked up a Tikka T3 223 1:8 twist, it had around .040 freebore. I throated it out for hevies using a ptg uni-throater which I rented from 4D. I added in a little precision by borrowing a set of reamer pilots for the best fit to my bore and made a bushing(bolt body o.d., throater handle I.d.) to keep the handle in line.
It was super simple to use and exact throat length is easy to achieve. I would recommend it to anyone who feels they have the mechanical aptitude.