the sizes do look strange out of context.
I've posted this before, perhaps even on this thread somewhere, but ISN 27-C is the third wrench in a 5-wrench Jeep set or a 6-wrench GMTK set, modeled after the 5- and 6-wrench sets that Bonney made and advertised in the early 1930's as the most efficient and effective set an automotive mechanic could possibly have, because of two features: (a), the set ranged from 3/8" to 1" without repeating an opening on any end, and (b), it included openings for common nuts and bolts in both USS and SAE standards. The US Army QMC seized on those features and modeled their on-board toolkits after it in their 1938 specification (Engineering Spec 422), which was taken right through the war and beyond. In turn, Bonney made a series of DOE wrenches in those sizes with the QMC drawing number ("585") embedded in their model number.
723: 3/8" x 7/16"
25: 1/2" x 19/32"
27-C: 9/16" x 11/16"
28-S: 5/8" x 25/32"
731-A: 3/4" x 7/8"
33-C: 15/16" x 1"
I stuck those and some other interesting research tidbits into a chapter ("Factory Toolkit, Spare Parts, and Accessories for the Willys MB") I co-authored with vaunted Willys CJ historian Fred Coldwell in Volume 5 of Lloyd White's
Evolution of the Willys MB series of books. (Not to shill. The books are expensive! I am working on a cheaper guide....

)