It's also not the same mechanism that's on the Committee, Handcraft Committee II or Centennial.
Interesting, I must say. Especially as these horns are separated by 20ish years.
Can you post a full pic or a few of your Contempora? I've seen a couple different ones (not to mention the SML Contempra stencils) and I want to be sure what you've got is what I'm thinking of.
FA Reynolds worked at FE Olds. Reynolds went on to form Reynolds Music Company, which was in turn bought by Olds. (Paul) Richards Music Company, then bought Martin around 1961, and then Olds merged with Norlin music (FA Reynolds) in 1964.