This is some information from Big Bore Sixguns by John Taffin.
In 1979, after a number of false starts,(Dick) Casull and Wayne Barker came together and the result was Freedom Arms.(pp.102, John Taffin) Dick Casull was the creator of the 454 Casull.
A few lines later:
in 1983, the first factory-built .454 Casull revolver from the new Freedom Arms Factory on the Wyoming/Idaho border was delievered in the beautiful Star Valley area of Freedom, Wyoming. (pp. 102, John Taffin)
The time line within those two quotes shows that this gun is one of the very first. If the gun is a 1980 year build then this gun would be prefactory production. The early 80's was a time period before there were Premier grade and Field grade revolvers. From my understanding all guns were produced as Premier grade at one time. Not till later was a Field grade produced. Due to this the very early guns did not have Premier grade written on them.
I hope this helps. The book listed above is an excellent read and I would suggest to anyone to invest in John Taffins writings. The books are not cheap but they are of excellent quality, full of information and well written.
Take Care,
Scott