Based on my research over the past few years, I believe the following presentation represents the chronological order of 5 oz class ingots produced by the Mint Of The United States At San Francisco from the early 1930's through 1959. It also represents all types known to date (5 oz class only).
A few placements are scientific; the Type I, large font, 999.75 fine ingots are found in M.H. Bolender coin auction catalogs from the early to mid 1930's. I place them first as I have found no earlier references anywhere to Mint of The United States At San Francisco silver ingots. One U.S. Mint Service Bar Delivery Receipt exists in my collection showing that some of the Type I, small font, 999.75 curved stem nine ingots were produced in December of 1942; this provides another scientific placement in the order. Type II, #217, is in numerical sequence ahead of ingots dated 1956, a third scientific placement. And finally the ingots stamped with 1959 hallmarks.
Type I, medium font ingots I place in the order to fit between the earliest produced and those know to have been produced in the early 1940's, and use numerical sequencing as well as fineness consistency to place the straight stem nine ingots before of the curved stem nine ingots.
The remainder of Type I, small font ingots are placed in the order using the same numerical and fineness characteristics. The #1093, Type I, small font ingot with straight stem nines is an anomaly as it is one of a kind so I have placed in in the transition position from numbered to unnumbered ingots given the fineness match of 999.5.
I have previously written about my theory of the unnumbered ingots bridging the gap between all of those above and the 1959 round dated hallmark ingots. In the presentation that follows on the second slide, the ingot castings and fineness are identical between the Type I, Type II and 1959, lending support to this bridge theory.
This remains a work in progress; I cautiously introduced this post with "I believe". Something may be discovered in 2015 that completely shakes this up and I look forward to any new discovery that helps document the history of these historical gems.