6mm Remington Wikipedia
The 6mm Remington rifle cartridge originally introduced in 1955 by Remington Arms Company as the 244 Remington is based on a necked down 257 Roberts cartridge itself a necked down 7×57mm Mauser using a 24/6mm for a combination of high velocity long range flat trajectory and accuracy it is suitable as a dual use hunting cartridge for both medium sized big game and varmints