DON'T. Just don't. In between the annular rings is soft timber, the rings are hard. Grit, soda or walnut shell blasting just eats the soft timber, it'll finish up looking like the beach when the tide goes out. All ripples. You'll knacker some potentially nice doors.
I was on a job where they did farmhouse beams, which looked fine, but they did the doors and a nice old table. I ended up putting a new top on the table, it was ruined.
Chemical stripping is the best way.