You've got a little variety, but not much. Remington loads it with a roundnose bullet, not the best long range ballistics there. Hornady loads it pretty warm, probably the best long range load you can get. I think Winchester used to load it, but I'm not sure if they still do. I'm not sure if Federal still loads it in it's Premium line, but the load used a Nosler Partition, 120 gr I think, at good velocity, around 2800 fps or so. Probably the best big game load.
Google custom ammo makers like CP Cartridge and Start & Stripes to see what they load. The ammo usually costs a bit more, but with what you gain, it's just about worth it if you don't want to handload. At CP the .257 loads tread right on the heels of the 25-06 loads.
Commercial 257 Roberts loads are generally loaded on the low side as there are many actions out there of questionable ability to handle higher pressures - Hornady and Federal make good ammunition to start with for the Roberts. Check Cabelas web site.
Prophet, I have a 1891 Argentine mauser action that I had converted to 257 Roberts a few years ago. I only shoot the Remington factory loads or my own hand loads in it. Based on my research, all other factory ammunition, Winchester, Hornady, Federal may be considered the 257 Roberts + ammo and with its higher velocities, yes it is hotter than the Remington ammo. My small ring 1891 Mauser action may not handle the pressures of the 257 Roberts + factory ammo, while any Remington, Winchester, Ruger and etc. factory made rifle should.
A forum community dedicated to the great outdoors and hunting enthusiasts. Come join the discussion about hunting, fishing, survival, archery gunsmithing, optics, reviews, accessories, classifieds, and more!