Thanks for the info. That led me to search a couple of different terms and I came up with THIS LINK
and this information.
"After a successful early career of hunting big game with a firearm (during which he designed several successful wildcat cartridges), Negley decided at age 40 that he had exhausted the rifle's challenges and took up archery. Of course, this was in an era that lacked all of today's instructional resources, and Negley acknowledged that he struggled at first."
This is information about William "Bill" Negley who was better know as a bow hunter, He lived 1914-2006 so would have been most active with his rifle work during a time when Niedner was in business. It's as good a SWAG as I have right now. At least I have a name to research and see if I hit pay dirt. Looks like he has a son still alive so a letter might get me some information.
Edited to add: Michael's book shows this to be a 1939 production barrel. Bill Negley would have been 25 at this date and that would be a reasonable age to assume he might have developed a cartridge and ordered a barrel or gained enough following that someone else did.