I've just acquired 2 M42 chinons - 300mm f5.6, 35mm f2.8.
These are two of a distinctive "tapered barrel" series made in the 1970's. it sounds like you have the 28mm from this series Ronald, and there is a review page for it
here. They are all (?) based on the equivalent early tamron adaptalls. Though as I mention in this
mflenses thread - p45, I was questioning whether the 35mm f2.8 might not be tamron, because tamron did not continue this focal length with the adaptalls.
There are some reviews here, and Bengt Sandberg has reviews of several of them, albeit with "Expert" nameplates, on his web site.
BKSPicture's Camera and Lens Reviews
I have done a fair amount of browsing and have yet to find anything firm or convincing to corroborate the tomioka attributions for
some chinons the "tapered barrel" chinons. Internet echos...? Cimko (cima Kogaku) attributions for later eg PK models seem likely however.
More discussion
here on mflenses. (Dcshooter already cited this link..)