280 o.k.h. info needed - unknown crtridge?

Hello all,

I recently acquired an experimental rifle that belonged to Elmer Keith. It is marked with the caliber 280 O.K.H on the side of the barrel. Although I find many references to other O.K.H. cartridges, I can only find 2 obscure one and two line mentions of the 280 O.K.H. cartridge. Does anyone have any information or know of a mention of this development?

I just looked in my pile of wildcat cartridges and I have a 285 OKH and not a 280. I seem to remember the 280 OKH was a 300 H& H based case…? sorry for the previous error in post.

Edited to correct error.

riflemagazine.com/magazine/P … artial.pdf

This article from Handloader Vol. 1-#4, magazine in 1966 has brief mention of the 280 OKH and a a picture of it. It is shown as 7mm OKH (experimental) based on the 375 H&H case.

1959 Guns Magazine in Keiths column, “Keith Says” brief discussion on 7mm cartridge development

"When I have to make hits on coyotes or
eagles out at long range, I prefer my heavy
barrel .280 O.K.H."
this quote from the May 1960 issue of Guns Magazine

Yes, I have seen the Handloader article. It mentions O’Neil’s experimental 7mm on a 375 H&H case but not specifically the 280 OKH.

I’ve also seen the “Coyotes and Eagles” comment which does specifically mention the 280 OKH.

I’ve also seen one other that mentions the 280 OKH; a comment in “Practical Dope on Big Bores” by F.C. Ness, (1948 ed) page 191.; about L.W. Youngberg suplying bullets for the OHK 280 Duplex cartridge.

I’d like to find other references and or rifles that may have existed.

Like Sportclay, the only reference I have about a 7 mm cartridge different than the 285 OKH that could be called 280 OKH is a wildcat based on the necked down 375 H&H case, very similar to the 7 mm STW but with more taper.
Anyway, the description says that it was a O’Neil development, there isn’t the Keith’s name.

The cartridges in the pictures you posted on other forums are very similar to the European 7 x 73 Vom Hofe ( developed in 1931 and described in american magazines in 1932). They are also very similar to the 280 Dubiel, which was loaded with .288" bullets.