5910 would be an early gun. Less than 300 made. Cataloged as a skeet model, but most had a trap style rib, although some have shown up with a field type rib. Built on the Competition receiver with trap grade wood.
Barrel codes:
1970__ T
1971__ U
1972__ W
1973__ X
1974__ Y
1975__ Z
1976__ I
1977__ O
1978__ Q
1979__ V