British Cartridges
450-400 Nitro Express in  3" case and 3&1/4" case versions,
also called .400 Jeffery Nitro Express in the 3" case version.
The 450/400 Nitro Express or 400 Jeffery Nitro Express was introduced in 1907 by Jeffery to replace the 450/400 BPE
(B.P.E. for Black Powder Express). (Nitro Express for Smokeless Powder or Cordite in 1907)
The 3" version case will have both “450-400 Nitro Express” and very early “400 Nitro Express” Head-stamps.
The 3" case version was introduced after the 3&¼""case version, as some of the 3&¼" cases  would stick inside the chamber
of the older 3&¼" case  B.P.E rifles after firing.