Here is what I know and what I've been told and what I can remember by Jerry Snetsinger who is or was the owner of the brass jawed Newhouses. They were all made in the smaller sized Newhouses up to the 114 Newhouse, not sure about the 4 1/2's or any of the Bear trap sizes. Jerry got them from Robbie Marshall, who originally had gotten them from someone out west, I believe it was Idaho, from what I can remember.
The collection had all the small sized Newhouse traps except, the 81 1/2, but the 81 1/2 has been owned by at least a couple known collectors, but Jerry could never get it bought to complete the set.
The story on the origin of the brass jaws, is when Oneida Community made new jaw molds for casting jaws, the first run through the molds was done with brass, because brass would show any imperfections in the molds. Oneida Community was very frugal and used every part they could, so some traps left the factory with the brass jaws, how many were made, is any ones guess.
The time period these were produced could span several years.
Along with the 81 1/2 there is also a 31 1/2 in the collection, two Newhouse traps that are very hard to find with regular cast jaws, let alone cast brass jaws.
That's about what I know on the subject, but if there is someone else that knows more, please jump in here and let us know more.