The 6mm Remington has exactly the same case dimensions as the .244 Remington. They differ only in the fact that the 6mm Remington is loaded with bullets of up to 100-gr., whereas the .244 Remington was never loaded with bullets heavier than 90-gr. Ammunition marked 6mm Remington can be fired in .244 Remington chambers and vice versa. However, rifles marked .244 Remington will not stabilize the 100-gr. bullets. These rifles feature a 1 in 12-inch twist (ideal for 80-gr. bullets), while the 6mm Remington rifles generally feature a 1 in 9-inch twist (ideal for 100-gr. bullets).