Prior to WWII, Keith and two of his associates Donald S. Hopkins and Charlie O'Neal, designed several wildcat rifle cartridges called the OKH (.280 OKH, .285 OKH, .333 OKH and .334 OKH) series.
The 280 O.K.H cartridge (O'Neal, Keith, Hopkins) is a .300 H&H Magnum necked down to .280 with no change to the shoulder angle or length. It was loaded with a custom (at that time) 180g bullet. You might call it a .280 H&H Magnum.
Keith developed it about 20 years before the 7mm Rem Mag was introduced in 1962.
It is nearly identical to the .280 DuBiel, another wildcat developed sometime during the time of Keith's 280 O.K.H.
