Some of the bullets and powders used by Horton in testing. Speer’s Loading Manual provided basic handload data.
The 6mm Rem. is nothing more than the 244 Rem., given a new name, different bullet weight and a change in barrel twist. To go a little farther back, the 244 came from the 257 Roberts, which first saw the light of day using the old tried-and-true 7×57mm Mauser case. The bullet diameter is hardly new either, as it dates back many years, both here and abroad. You never heard of the 6mm Lee Straight Pull rifle?
The 244 Rem. and the 243 Win. came out about the same time, but the 244 lost the race rather early when it was found that the twist used, 1–12″, wouldn’t stabilize bullets of 100 grains or heavier if spitzer pointed. The 244 was first loaded with 75- and 90-gr. bullets while the 243 was available with 80- and 100-grainers. With the 243’s 1–10″ twist no troubles were had with 100-gr. sharp pointed bullets. Remington had looked on the 244 as mainly a varmint cartridge, but the public found the 243 a pretty good deer cartridge, so much so that 250–3000 and 257 Roberts sales hit rock bottom as a result. Regrettable, too, for both loads make darned fine cart ridges when reloaded.
Remington finally saw the light and changed the twist of the 244 to 1–10″, but for some reason they never did say much when this was done. Probably too late to do much good anyway. With the introduction of the Remington 700 rifles a “new” cartridge, the 6mm Remington, also made its appearance. There are no specification differences between the 244 and the 6mm Rem., but reloaders should reduce the 244 charges a bit before using them in the 6mm Rem., if only because of the faster twist of the latter.
6mm cartridges were originally loaded only with 100-gr. bullets, but late in 1965 an 80-gr. loading was announced. Pleasing news to the non-reloading varmint hunters.