.244 Remington / 6mm Remington (using Sierra bullets)
Date: May 07 2020
Both the .244 Remington and .243 Winchester were introduced in 1955. Both were based on similar wildcats developed by Fred Huntington, Warren Page and others. The .244 was based on a necked down .257 Roberts case, while the .243 Winchester was based on a necked down .308 Winchester. As a result, the .244 had greater powder capacity and could reach higher velocities. Remington viewed its cartridge primarily as a varmint round and selected a one-in-12-inch rifling twist that best stabilized 50-to 80-grain (and sometimes 90-grain) Varmint bullets. On the other hand, Winchester recognized the .243 as suitable for deer and varmints and chose a 1:10 twist value of Winchesters dual purpose cartridge, and it became widely popular while the Remington cartridge fizzled. Some reports indicated that for every .244 Remington rifle sold, there were ten .243 Winchesters sold.
Beginning in 1963, Remington renamed the .244 to 6mm Remington with all chamber dimensions being the same, and the cartridge was loaded with heavier bullets for hunting big game. Along with the new named Remington also changed the barrel twist to a one-turn in 9 inches. Either cartridge can be fired in .244 or 6mm rifles but the slow twist rate of .244 rifles will not usually stabilize 100-grain (and heavier) bullets.
The 6mm Remington is an excellent, well designed cartridge; however, with its late start, so to speak, it has never gained the widespread popularity of the .243 Winchester. It does offer a performance advantage and has earned a loyal following. The only Remington factory load currently available advertises a 100-grain bullet at 3,100 fps. From the 22-inch barrel of the Ruger M77 MKII test rifle actual velocity was 2,977 fps. Using Sierra 100-grain SPT and SBT bullets, factory load velocities were more or less duplicated using IMR-4895, IMR-4320, IMR-4350 and IMR-4831 powders.