SBT

Here is a post from the old message board that I think answers your question.

I also have a question - Does anyone know who "owns" the term with regard to firearms and cartridges today? ie If someone wanted to introduce say a .750 Nitro Express, could they? Is it an open term"

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From: Nitro (Original Message) Sent: 12 Jul 2002
I recently received an email asking about the origins of the name "Nitro Express".

Whether they were so named because the propellant contained nitro glyserine rather than gun powder.

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The "Nitro Express" cartridges were introduced when the standard propellant was black powder. Some of the earliest cartridges were the 500 Nitro Express in the 1890's, the 577 Nitro Express and the "small bores" the 450 3 1/4" NE introduced by Rigby in 1898 and the 500/450 3 1/4" NE by Holland & Holland around 1900. These cartridges replaced the 4, 6 and 8 bore blackpowder elephant guns with lighter, smaller more effective calibre rifles pushing projectiles powered by cordite.

Cordite was a smokeless propellant in the form of long "cords.

The "Nitro" is derived from nitric acid. Nitro-cellilose is cellulose treated with nitric acid, and is the base for the "nitro" smokeless propellants.

"Express" was a marketing term to promote fantastic velocities (like 2,000 fps!) similar to "magnum" today, and was associated with the "fast" trains of the era, "Express Trains". Similarly some Black Powder cartridges were labelled "Black Powder Express".

Nitro Proofing was originally the process of testing or "proofing" the black powder firearms of the day with the new smokeless propellants which generated considerably higher pressures.

Nitroglycerin on the other hand is an explosive liquid made from glycerol and nitric and sulphuric acids.