Re: B Baker .30 FBI Rem 700
It appears to be very much like a 30-338, except that the shoulder is pushed back another 0.10", to form a longer neck.
When I had a 30-338, I formed my brass from WW 338 brass with a single pass neck down.
If you don't have dies, then give Redding, RCBS or Huntington's a call. Huntington's was always very helpful to me when I had a wildcat that needed feeding. Z-Hat also lists chambering reamers of the 30 FBI. They make custom dies as well.
Bob