Not sure if any of this is valid.
I have not heard that name in/around the industry since about 2010 but do see that he was last seen on LRH forum in 2015.
Zethilius Associates 3630 Cincinnati Ave Ste B. Rocklin, CA 95765
fflgundealers.net
Probably only a few of the old timers that were dedicated ELR geeks have ever heard of his desires/dreams.
One of those was a high temp/high pressure barrel that was to be used with some new cartridge case designs that were to operate with RDX/HMX based propellants.
It would be intriguing to see where his brain is at in today's era. Hopefully someone can help you.