.375 Flanged Nitro Express  The .375 Nitro Express 2½ inch Velopex , was a nitrocellulose (smokeless) powder cartridge introduced in 1899. A hunting cartridge produced for single-shot and double rifles, the .375 Flanged NE is a slightly longer version of the .303 British necked out to .375 caliber. The .375 Flanged Nitro Express should not be confused with the .375 Flanged Magnum, a much longer and more powerful all-round African hunting cartridge. The .375 Flanged NE is not considered suitable for hunting dangerous game, but is considered a good low velocity medium bore cartridge for woods and plains game with superior performance to the .45-70.