AFAIK, ther were two separate Hoffman's making guns before WWII, Frank & George.
http://www.hoffmanarms.com/HoffmanHistory.html
(Frank) Hoffman Arms eventually moved from OH to TX, then OK, and later became Dubiel Arms in the 1940's.
Geo Hoffman made rifles in .416 Hoffman, a blown-out .375H&H.
This is a pic of .400 Hoffman Mag brass that Midway had - so I would presume a .450 on the same case would be very similar to a .458 Winchester Mag or the .450 Lott - don't forget, these rifles/chamberings were well before the .458 Winchester mag was born, and
everybody was experimenting with big bore rifles for an African safari.
A .450 Hoffman on a Remington 1917 sounds like a custom gunsmith job from the same era.
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