I have RCBS dies for this gun and by looking at those, the base diameter of the case looks like H&H size. I'm thinking it must be based on the H&H case as is the .350 G&H.
Interesting that all of these "wildcatters" ended up with such similar cartridges.
For instance, your .333OKH must be very similar to a .35 Whelen. Your buddies .334OKH Mag. must be just about identical to my .333G&H.
Seems to me that if you had a battery of rifles in chamberings with a common base shell such as
25-06, 30-06, 35 Whelen. Or .280 Dubiel, .300H&H, .333 or .350G&H, .375H&H and had resizing dies for each, you would be set. At least for North American game. Imagine a takedown rifle with three or four different barrel options. (please, nobody suggest TC Encore, please!!)